Cathodic device of aluminum electrolyzer. RU patent 2245397.
 Impregnated graphitic cathode for electrolysis of aluminum / 2245396The invention presents an impregnated graphitic cathode for production of aluminum by electrolysis and is pertinent to the field of metallurgy, in particular, to production of the graphitic cathodes used in production of aluminum by electrolysis. The invention offers an impregnated graphitic cathode for electrolysis of aluminum and a method of its production. The cathode contains in its pores an impregnating product heat-treated. At that in the capacity of the impregnating product the cathode contains a carboniferous product heat treated under the temperature of no less than 1600°С to provide resistance to erosion at the expense of protection by the formed graphitized binding substance. The method includes production of the graphitic cathode, its impregnation by dipping into the impregnating product in vacuum and a thermal treatment. At that the graphitic cathode is produced from coke, with graphite or without it, and also from a pitch, and before impregnation it is exposed to calcination at the temperature exceeding 2400 °С. The impregnation is realized by a carboniferous product at the temperature of its viscous state and the thermal treatment of the impregnated cathode is conducted at the temperature of less than 1600 °С, but sufficient for hardening and-or sintering of the impregnating product and formation of the non-graphitized coal layer for protection of graphitizing binding substance against erosion. The technical result is an increase of service life of the graphitic cathode. |
 Graphitic cathode for electrolysis of aluminum / 2245395The invention presents a graphitic cathode for electrolysis of aluminum and is dealt with the field of metallurgy, in particular, with the graphitic cathodes used in production of aluminum by an electrolysis. The graphitic cathode for electrolysis of the aluminum is produced by graphitization of the cathodic block from a carbonaceous material. At that the cathode is made as the entire block with different specific electrical resistance along its longitudinal axis. At that the specific electrical resistance in the end areas of the cathode is more, than in its central area. The technical result - increased service life of the graphitic cathode at the expense of increased erosion resistance in the end areas of the cathode. |
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Graphitic cathode for electrolysis of aluminum / 2245395 The invention presents a graphitic cathode for electrolysis of aluminum and is dealt with the field of metallurgy, in particular, with the graphitic cathodes used in production of aluminum by an electrolysis. The graphitic cathode for electrolysis of the aluminum is produced by graphitization of the cathodic block from a carbonaceous material. At that the cathode is made as the entire block with different specific electrical resistance along its longitudinal axis. At that the specific electrical resistance in the end areas of the cathode is more, than in its central area. The technical result - increased service life of the graphitic cathode at the expense of increased erosion resistance in the end areas of the cathode. |
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Impregnated graphitic cathode for electrolysis of aluminum / 2245396 The invention presents an impregnated graphitic cathode for production of aluminum by electrolysis and is pertinent to the field of metallurgy, in particular, to production of the graphitic cathodes used in production of aluminum by electrolysis. The invention offers an impregnated graphitic cathode for electrolysis of aluminum and a method of its production. The cathode contains in its pores an impregnating product heat-treated. At that in the capacity of the impregnating product the cathode contains a carboniferous product heat treated under the temperature of no less than 1600°С to provide resistance to erosion at the expense of protection by the formed graphitized binding substance. The method includes production of the graphitic cathode, its impregnation by dipping into the impregnating product in vacuum and a thermal treatment. At that the graphitic cathode is produced from coke, with graphite or without it, and also from a pitch, and before impregnation it is exposed to calcination at the temperature exceeding 2400 °С. The impregnation is realized by a carboniferous product at the temperature of its viscous state and the thermal treatment of the impregnated cathode is conducted at the temperature of less than 1600 °С, but sufficient for hardening and-or sintering of the impregnating product and formation of the non-graphitized coal layer for protection of graphitizing binding substance against erosion. The technical result is an increase of service life of the graphitic cathode. |
 Cathodic device of aluminum electrolyzer / 2245397The 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. |
 Aluminum cell / 2256009Cathode casing of aluminum cell includes lengthwise walls with windows for outlet of cathode rods, end walls, bottom and ring frames rigidly joined with walls and bottom. In order to lower labor consumption, simplify mounting and dismounting operations. Ring frames adjacent at least to one of lengthwise walls (except boundary ring frames) from their upper part till inner edge in range of height of windows for outlet of cathode rods are freely adjoined to said lengthwise wall. According to other variant of invention at least one lengthwise wall is detachable. Parting places of said wall are arranged between boundary ring frames in range of height of windows for outlet of cathode rods. In parting places members providing rigid joint of detachable wall with fixed portion of casing wall are mounted. |
 Method of forming protective coating for carbon containing components of electrolysis cell / 2257425Method comprises steps of preparing liquid suspension of refractory material dispersed in solution of lignosulfonate binder; applying suspension as coating on surface of carbon containing component; drying coating. |
 Side lining of aluminum electrolyzer / 2263162Proposed side lining includes interconnected members - plates and blocks made from non-metallic refractory compounds possessing high resistance and interconnected by means of end faces in form of inversed symmetrical projections and recesses and adhesive or cementing mix. Plates and blocks are made from silicon carbide. Angular blocks are made in form of strip, 70 mm thick and 600-800 mm long which is bent at center around longitudinal axis at angle of 90° relative to vertical whose end faces are inclined at angle of 18° relative to vertical and are narrowing downward by 219 mm each. End faces are made in form of inversed symmetrical projections and recesses at radius of 14-15 mm which are parallel to vertical axis of walls of aluminum electrolyzer. |
 Cathode facing to aluminum cell / 2266983Cathode facing includes carbon blocks, heat insulation layer and refractory part having two protection layers, upper layer adjoining to carbon blocks and lower layer made of powder materials. Upper protection layer includes alumosilicate composition resistant against action of electrolyte components containing 27 -35% of Al2 O3 with fraction size no more than 2.5 mm and with thickness consisting 10 - 50% of height of refractory part. Lower protection layer is made at least of one sealed metallic vessel filled with refractory material including carbon-containing composition resistant against action of melt aluminum and electrolyte components and having heat conductivity factor no more than 0.1 Wt/(mK). In lower protection layer vessels are filled with carbon black; thickness of said layer consists 50 - 90% of height of refractory part. |
 Method of mounting side lining of cathode device for aluminum electrolyzer / 2270887Proposed method includes mounting the heat-insulating and refractory components of electrolyzer and applying protective material on base of covalent nitrides to surface of side lining. Used as protective material is boron nitride-based material which ensures reduction of after-start period, increases electrolyzer service life, enhances aluminum grade, increases yield by current and daily productivity of electrolyzer; protective material is applied flush with top in continuous layer. Lower boundary of coat is located below "electrolyte-metal" interface. Thickness of coat is maintained within 0.1-1 mm. Open surface porosity is maintained within 2-3%. Consistency of material of coat changes from fluid to viscous-flow state. Application of coat is performed by spraying, painting or concrete-spraying method. |
 Method of forming hearth for aluminum electrolyzer / 2270888Proposed method includes preliminary estimation of quality of hearth modules by proximate ultrasonic inspection, mounting of complete set of hearth modules and forming of hearth; electrolyzer is equipped with hearth modules at inhomogeneity index not exceeding 0.65 relative units according to ultrasonic inspection; inhomogeneity index is determined by the following formula Iinhom = (tmax/tmin-1), where Iinhom is inhomogeneity index according to ultrasonic inspection; tmax is maximum magnitude of index of ultrasonic inspection for definite electrolyzer; tmin is minimum magnitude of index of ultrasonic inspection for definite electrolyzer; hearth is formed in such way that adjacent modules with close indices of ultrasonic inspection are mounted in longitudinal and transversal directions; modules with minimum indices of ultrasonic inspection are mounted in center of hearth at smooth increase of this index toward end faces of electrolysis bath. |
 Method of mounting cathode section of aluminum electrolyzer / 2270889Current-supply metal rod is placed in slot of carbon block on layer of carbon-containing conducting material. Surface of carbon block slot is preliminarily coated with carbon-based surfactant and layer of carbon-containing conducting material is compacted by vibration applied on current-supply metal rod, thus ensuring reliable electromechanical "conducting rod-carbon block" contact and reducing probability of penetration of aluminum melt into hearth body. At application of vibration in local zone on side of flush area, maximum reduction of voltage drop is ensured in contact layer between rod and block slot. Maximum thickness of layer of carbon-containing conducting material before vibration is equal to optimal magnitude determined by definite formula. |
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 TiB 2 , TiC, TiN, ZrB 2 , 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: the use of scarce and expensive materials (nitrides, 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 TiB 2 , which are connected to the backbone, 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 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 (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 consists in the following.
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 cell through 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 work.
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 may 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 of electrolytic production of aluminum, by loading components (material) cover the pot with supplies, education in the process of electrolysis necessary connections (TV 2 , ZrB 2 , 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 coating;
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 TV 2 [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 coating 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 heat-insulating and refractory 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 joints.
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% to increase the output 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.