Cathodic device of aluminum electrolyzer

FIELD: nonferrous metallurgy; production of aluminum by electrolysis of fused salts.

SUBSTANCE: the invention I pertinent to nonferrous metallurgy and may be used in a design of electrolyzers for production of aluminum by electrolysis of fused salts. The technical result of the invention is hardening of a hearth, a decrease of thickness of a metal layer on the hearth and an interpolar space, a decrease of speeds of circulatory flows of cathodic metal, a decrease of losses of current. The cathodic device contains a lined cathodic housing and a hearth made out of from carbonaceous blocks with channels of a rectangular cross section. On the surface of the hearth there is a wetted with aluminum cover and the channels have the length equal to the width of the stack of the cathodic device, and with a width equal 1,1-2,2 well of the carbonaceous block, depth, equal to 0.2-0.4 of height of the carbonaceous block and thy are formed by the lateral longitudinal surfaces of the carbonaceous blocks and the carbonaceous blocks of the lateral cathodic lining. The electro-conductive cover wetted with aluminum is made out of titanium diboride.

EFFECT: hardening of a hearth, a decrease of thickness of a metal layer on the hearth and an interpolar space, a decrease of speeds of circulatory flows of cathodic metal, a decrease of losses of current.

2 cl, 2 dwg

 

The invention relates to ferrous metallurgy and can be used in the construction of electrolytic cells to produce aluminium by the electrolysis of molten salts.

In industrial electrolysis furnace hearth cathode devices are typically from coal materials and has a horizontal surface without projections and depressions. In the process of electrolysis from the interaction of magnetic fields with horizontal currents in the metal formed a circulation flow that negatively affect the technical and economic performance: metal loss, the decrease in the output current, the increase in energy consumption.

Known electrolytic cell for aluminium production (patent Switzerland No. 643600 25 With 3/08, publ. 15.06.1984, [1]), in which to eliminate the harmful influence of flow patterns on the furnace hearth place a layer of bulk materials with a particle size of >0.1 mm, a thickness of 20-50 mm from TiB2, TiC, TiN, ZrB2, ZrN, or mixtures of these materials. The metal level support for 1-3 mm above the layer of bulk materials, the furnace hearth can be made inclined, it can be installed permeable to liquid metal partition separating the liquid aluminum into compartments, one of which is at the bottom of the bottom left free from bulk materials to extract a liquid aluminum.

The disadvantages of the known solutions: using the Def is zitnik and expensive materials (nitrides, the borides, carbides of titanium and zirconium), complicated the process of cleaning from the bottom sediments, covering the bottom.

Known electrolytic cell for aluminium production, including anode, cathode and replaceable elements of conductive refractory material (French patent No. 2508496 25 With 3/06, publ. 31.12.82, [2]), in which for the suppression of the circulation flow of the metal at the cathode is placed replaceable elements of electrically conductive refractory material. When this cathode block has an intermediate inert support and the active elements of conductive material, such as TiB2connected with the support, but can be separated from it. The density of the support and active elements higher than the density of liquid aluminum. The active elements can be in the form of sliders, flat-head, provided with ribs and vertical process, and are located in holes formed in the support.

The disadvantages of the known electrolytic cell: the complexity of installation, significant material and labor for installation and maintenance of cells.

Known electrolytic cell for obtaining aluminium, containing lined cathode casing with the furnace hearth of carbon blocks, in order to enhance the yield of the aluminum current by reducing the speed of the circulating flow of the cathode metal, the furnace hearth is made with channels formed longitudinal faces of the two designexperience blocks, the depth of 0.08 to 0.2 and width of the upper base of 0.1-0.5 of the height of the block (As the USSR №1444401, With 25 3/06, 1988 [3]).

The circulation rate of the cathode metal is reduced from 6-10 cm/s up to 1-2 cm/s, which is accompanied by an increase in output of aluminum current 2-3%.

The technical essence, the presence of similar features this decision was made as the nearest equivalent.

The disadvantages of the known solutions: reducing the resistance of the bottom interblock seams, reducing the effective service life due to overgrowth of channel sediment.

The objective of the proposed technical solution is to increase the service life of the cell due to the increasing resistance of the bottom and increase the efficiency of the electrolysis process.

Technical results are: strengthening the bottom without reducing the conductivity, reducing the thickness of the metal on the furnace hearth and the interpolar distances, speeds are reduced circulating flow of the cathode metal, reducing current losses due to the improvements produced in the furnace hearth.

Technical results achieved by the fact that cathode device aluminum cell that contains lined cathode casing and the furnace hearth of the carbon blocks with channels of rectangular cross-section, on the surface of the hearth is made wettable conductive aluminum coating, the channels of rectangular cross section made of length equal to the width of mine cathode device, the width equal to 1,1-2,2 width of the carbon block, the depth equal to 0.2-0.4 height of the carbon block, and is formed of longitudinal side surfaces of the blocks and the carbonaceous blocks the side of the cathode lining.

Conductive wetted by the aluminum coating made of titanium diboride.

The technical essence of the proposed solution is as follows.

It is known that in industrial electrolyzers during the operation of observed adverse effects that reduce technical and economic indicators of the electrolysis process. As a result of interaction of the magnetic field with a horizontal currents in the metal arise transverse electromagnetic forces, which cause the formation of circulating flows. The consequence of the existence of such flows, which is stronger, the more power the electrolyzer are significant fluctuations in the surface of the metal, the oxidation Korolkov metal involved in the electrolyte, resulting in reduced output current (Handbook of metallurgy of nonferrous metals. The production of aluminum, metallurgy, M., 1970, s [4]).

In the proposed solution to reduce the intensity of the circulation flows diminish the force of interaction of magnetic fields from currents in the metal, reducing the height of the active layer of metal in the mine cathode device of the electrolyzer through the implementation of the program channels in the furnace hearth. Running on the furnace hearth protective wettable conductive aluminum layer, such as titanium diboride, gives the following results: increasing the resistance of the bottom due to the reduction and prevention of penetration of sodium in coal blocks, the improvement is produced in the furnace hearth, the reduction of the voltage drop in the cathode, the possibility of reducing the interpolar distance. Using a combination of technical results obtained will allow to increase the output of the aluminum current and lifetime of the cell.

The size of the executable channels allow for cleaning and to increase the duration of their effective operation.

The execution of the channels deeper than 0.4 height of the carbon block is impractical because of the possibility of reducing the resistance of the bottom and reduced service life of the cell.

On the ends of the shaft channels are made deeper, which provides technological spout metal from the electrolytic cell. Depending on the design characteristics of the cells, the sizes of the blocks, the number of channels, the width and depth of the channels, in the present limits are subject to change.

The floor is made of electrically conductive wetted by aluminum material, such as titanium diboride, and can be applied in different ways when mounting the cathode of the device, and preferably, in the process electrolyte the institutions to produce aluminium by loading components (material) cover the pot with supplies, education in the process of electrolysis necessary connections (TV2, ZrB2, TiC) and planting them on the coal furnace hearth.

From the nearest analogue of the proposed solution differs as follows:

- on the entire surface of the hearth is made conductive, wetted aluminum floor;

bottom channels are the surface of the carbon blocks and the top interconnect joints, and do not interconnect the seam;

- dimensions-running channels: length equal to the width of the cathode of the device, the width equal to 1,1-2,2-width carbon block depth equal to 0.2-0.4 height of the carbon block.

The above differences allow us to conclude about the relevance of the proposed technical solution the criteria of the invention of “novelty.”

Comparative analysis of the proposed solution with the closest analogue and other known solutions in this area revealed the following:

- it is known to run on the furnace hearth cathode device replaceable components of the electrically conductive refractory material, for example TV2[2];

- it is known to run on the furnace hearth channels formed by the longitudinal edges of two adjacent carbon blocks, a depth of 0.08 to 0.2 and width of the upper base of 0.1-0.5 of the height of the block [3];

- known deposition on carbon cathodes cover the Oia of refractory borides of the suspension, consisting of particles obtained in advance of boride in a colloidal carrier, which is dried and heated for hardening (RF Patent No. 2135643, With 25 3/06, 1999 [5]);

- there is a method of creating and maintaining a protective surfaces on carbon cathodes in electric furnaces for melting aluminum, which creates and maintains carbon cathode blocks of the device protective layer boride titanium, and sources of boron and titanium in the cell is the charge (U.S. Patent No. 5618403, With 25 3/08, 1997 [6]);

well - known furnace hearth aluminum electrolysis cell in which the cathode blocks in the upper part along their entire length have a groove with sloping walls and a depth of 1/4 of the total height of the block (As the USSR №281825, C 22 D 3/02, 1970 [7]).

Not identified in the search and comparative analysis of technical solutions, characterized by a set of signs that are identical or equivalent to the combination of features of the proposed solution and giving in their use of similar or higher technical and economic results, which allows to make a conclusion about its compliance with the criteria of the invention “inventive step”.

Figure 1 shows a cross-section of the cathode of the device. Figure 2 shows a longitudinal section of the cathode of the device.

The device cathode consists of a metal cathode casing 1, provided with thermal insulation and Ogneupory the th lining 2, the side and end lining of the blocks 3 and the blocks of the bottom 4. Carbon blocks 4 are interconnected with the side and end carbon carbon lining sole weight which filled interconnect 5 and 6 peripheral seams.

The channels in the furnace hearth is formed by surfaces of the blocks of the bottom 4, side and end linings of carbon units 3 and seams 5, 6.

The furnace hearth carbon blocks and also channels) is provided with a refractory conductive coating of titanium diboride 7, obtained during the start of the electrolysis cell using a boron-containing raw material, forming the titanium incoming raw materials, diboride, disembark on the furnace hearth. Maintaining such coverage in your state is performed by applying a working cell boron compounds.

The proposed construction of the cathode device aluminum cell will provide:

1) decrease the speed of the circulating flow of the cathode metal;

2) reducing negative for the process of interaction of magnetic fields with horizontal currents in the metal;

3) the improvement is produced and reducing current losses in the furnace hearth;

4) reduction of the interpolar distance.

The above technical results will allow to reduce by 300-400 kWh energy consumption and 1.5-2% increase is yhod current, to increase the service life of the bottom for 6-8 months.

1. Cathode device aluminum cell that contains lined cathode casing and the furnace hearth of the carbon blocks with channels of rectangular cross-section, characterized in that on the surface of the hearth is made wettable conductive aluminum coating, the channels of rectangular cross section made of length equal to the width of mine cathode device, the width equal to 1,1-2,2 width of the carbon block, the depth equal to 0.2-0.4 height of the carbon block, and is formed of longitudinal side surfaces of the carbon blocks and the carbonaceous blocks the side of the cathode lining.

2. The cathode device according to claim 1, wherein the wettable conductive aluminum coating made of titanium diboride.



 

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4 cl, 2 dwg, 1 ex

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4 cl, 4 dwg, 1 tbl

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