Method of obtaining of cathode pack for electrolyser for aluminium production and cathode pack

FIELD: metallurgy.

SUBSTANCE: invention relates to the method of obtaining of an electrolyser cathode pack for aluminium production. The method includes preparation of initial materials containing coke and powder of solid material such as, for example TiB2, and also, if necessary, carboniferous material, mixing of initial materials, formation of the cathode pack, carbonisation, graphitisation and cooling, note that graphitisation is performed at temperatures from 2300 up to 3000°C, in particular from 2400 to 2900°, and the second layer made with the thickness amounting from 10 up to 50%, in particular from 15 up to 45% of the total thickness of the cathode pack.

EFFECT: high wear resistance with reference to aluminium and cryolith, and decrease in energy consumption are provided.

8 cl

 

The present invention relates to a method for producing a cathode Assembly for electrolytic cell for producing aluminium and the cathode block.

The known method of production of metallic aluminum is a method of Hall-Heroult. In this electrolytic method, the bottom of the electrolysis cell is typically formed of cathode surface, which consists of individual cathode blocks. Bottom cathode contact via steel rods that are inserted into the corresponding elongated recess on the bottom side of the cathode blocks.

The production of cathode blocks is usually performed by mixing the carbon-containing coke particles, such as anthracite, carbon or graphite, sealing and carbonation. If necessary, this directly follows the stage graphitization at elevated temperatures in which the carbonaceous particles and coke is at least partially transformed into graphite.

As a result of graphitization significantly increases the conductivity of the material of the cathode, and the electrical resistivity is greatly reduced.

However, graphitized carbon and graphite poorly or not wetted by molten aluminum. The result is increased demand for electricity and, thus, the need of the cell for energy.

To solve this problem, according to the prior art, in pove�chestny layer cathode block is administered TiB 2. This is described for example in DE 112006004078. This surface layer, which is a composite TiB2and graphite, is in direct contact with molten aluminum and thus is crucial for supplying current from the cathode in the aluminum melt. TiB2and similar solid ceramic materials lead to the improvement of the wettability of the cathode in the graphitized state and, thus, better energy efficiency of the electrolysis process. Solid ceramic materials may, in addition, to increase the bulk density and hardness of the cathode, which results in better wear resistance against, in particular, to the molten aluminum and cryolite. Solid materials are also called RHM (refractory hard material - refractory solid material).

However, the powder TiB2and similar powders of solid materials in the process of graphitization partially lose their wettability and the effect of improving the wear resistance.

Therefore, the object of the present invention is to devise a simple method of producing the cathode composite TiB2and graphite, which is well wetted by liquid aluminum and has good properties in respect of wear and tear, as well as to develop a corresponding cathode block.

This problem is solved by a method according to claim 1 of the claims.

By the invention a method of producing cat�defined block contains the stages of preparation of raw materials, containing coke powder and solid material, such as TiB2and also, if necessary, other carbonaceous material, the steps of mixing the starting materials, forming the cathode block, carbonization and graphitization and cooling and is characterized in that the stage of graphitization is carried out at temperatures ranging from 2300 to 3000°C, in particular from 2400 to 2900°C.

Especially preferred proved to temperatures below 2900°C, as usual TiB2does not melt up to 2900°C. Although the melting presumably does not lead to any chemical change TiB2since x-ray diffraction showed the presence of TiB2in the cathode block and after melting and subsequent cooling. However, as a result of melting of the fine particles of TiB2can be collected in larger particles. A certain danger is that the liquid TiB2uncontrolled moves through the open pores.

In the temperature range according to the invention, the graphitization process continues as long as there is high thermal and electrical conductivity of carbon-containing material.

Preferably, the stage of graphitization is performed at an average heating rate from 90 to 200 K/h. Alternative or additionally, the temperature of graphitization is maintained for a period from 0 to 1 h. PR� these heating rates and the duration of incubation are achieved particularly good results in respect of graphitization and obtain a solid material.

Preferably, the duration of the heat treatment, calculated prior to cooling, can be from 10 to 28 hours.

It may be preferred that the composite hard material and graphite or graphitized carbon forms the entire cathode block. It is preferable that only need one part to be processed mass and, accordingly, only one stage of mixing.

Alternatively, it may be preferred that the cathode unit contains at least two layers, wherein the layer of composite material forms a second layer of the cathode block. This second layer is in direct contact with the melt in the cell of the cell.

Preferably, the cathode unit comprises at least one other layer (hereinafter referred to as the first layer), which contains less powder solid material than the surface layer, or contains no solid powder material. This reduces the number of costly powder solid material. The first layer with the introduction of cathode in an aluminum electrolytic cell is not in contact directly with the molten aluminum and therefore not obliged to have good wettability and durability.

The second layer may preferably have a thickness equal to from 10 to 50%, in particular 15 to 45%, from the full thickness of the cathode block. Small thickness W�of the second layer, for example, 20%, may be preferable, since in this case you need only a small amount of expensive solid material.

Alternatively, it may be preferable to a larger thickness of the second layer, for example, 40% as a layer which contains a solid material, has high wear resistance. The more is the thickness of this highly wear-resistant material of the total thickness of the cathode block, the higher the wear resistance of the cathode unit as a whole.

Preferably, the coke includes two varieties of coke with different characteristics volume changes during carbonization and/or graphitization, and/or cooling.

Unexpectedly, the service life of the cathode blocks obtained in this way, significantly higher than that of the cathode blocks obtained by the conventional method.

Preferably, the carbon fraction of the cathode block is compacted to a bulk density above 1,68 g/cm3in particular above 1,71 g/cm3in particular to 1.75 g/cm3.

It is assumed that the increased bulk density preferably enhances life. This can be based, firstly, on the fact that per unit volume of the cathode block has more mass for a given mass removal rate per unit time leads to a higher residual mass after a given duration� removal. Secondly, it can be assumed that the higher bulk density together with the corresponding lower porosity prevents infiltration of the electrolyte, which acts as a corrosive environment.

In this embodiment, the advantages of the present invention the temperature of graphitization from 2300 to 3000°C can be combined with increasing the bulk density of the cathode block. Thus, preferably at least partially offset the effects of incomplete graphitization.

Since the second layer by the addition of solid material after graphitization always has a high bulk density, for example, above 1.80 g/cm3preferably, if the first layer after graphitization also has a high bulk density, component according to the invention above to 1.68 g/cm3. A small difference of thermal expansion coefficients and bulk density on the stages of the heat treatment reduces the period of production and the percentage of defective cathode blocks. In addition, the application preferably also increases the resistance to thermal stresses and damage caused by them.

Preferably, two varieties of coke contain first grade coke and second grade coke, the first grade of coke during carbonization and/or graphitization, and/or cooling has stronger compression and/or expansion, �eat second grade coke. With greater compression and/or expansion is the preferred option the implementation of the different characteristics of changes in the volume, which, presumably, is particularly well suited to lead to stronger seal than when mixed varieties of coke, which have the same compression and/or expansion. With greater compression and/or expansion refers to any temperature interval. For example, a stronger compression of the first coke can only take place with the carbonation. On the other hand, additionally or alternatively, a stronger expansion may occur in the transition region from carbonization to graphitization. Alternative or additionally, different characteristics volume changes can occur during cooling.

Preferably, the compression and/or expansion of the first grade of coke during carbonization and/or graphitization, and/or cooling, based on volume of at least 10% higher than that of second grade coke, in particular, at least 25% higher, in particular at least 50% higher. Thus, for example, in the case where the compression of the first grade of coke is higher by 10% at a temperature of from room temperature to 2000°C compression at the second grade coke is 1.0 vol.%, while the first grade of coke, on the contrary, 1.1%.

Preferably, the compression and/or expansion of the first with�the coke during carbonization, and/or graphitization, and/or cooling, based on volume of at least 100% higher than second grade coke, in particular, by at least 200% higher, in particular at least 300% higher. Thus, for example, in the case where the extension of the first grade of coke above 300%, the extension of second grade coke at a temperature of from room temperature to 1000°C is 1.0 vol.%, while coke first grade to 4.0 vol.%.

The method according to the invention also covers a case where the first grade of coke is experiencing compression, and second grade coke in the same temperature interval feels, on the contrary, the. Thus, the compression and/or expansion of over 300% is, for example, to the case when the second grade coke is compressed by 1.0 vol.%, and the first grade of coke, on the contrary, expanding by 2.0%.

Alternatively it is possible that in at least any one temperature interval of the method according to the invention greater compression and/or stretching described above for first grade coke, had not first grade coke, and second grade coke.

Preferably, at least one of the two varieties of coke is petroleum coke or coke on the basis of coal tar pitch.

Preferably, the quantitative proportion (in weight percent) of second grade coke is from 50 to 90% of the total number of coke. In this quantitative�enom range of different characteristics of changes in the volume of the first and second grade coke is particularly well affect the seal of carbonization, and/or graphitization, and/or cooling. Possible preferred quantitative ranges of second grade coke can be from 50 to 60% and from 60% to 80%, even 80 to 90%.

Preferably, to add to the coke in at least one carbonaceous material, and/or pitch and/or additives. It may be preferable both from the point of view of the suitability of coke for processing, and from the point of view of the subsequent properties of the obtained cathode block.

Preferably, additional carbonaceous material comprises graphite material, in particular, additional carbonaceous material comprises graphite-bearing material, such as graphite. Graphite may be synthetic and/or natural graphite. Due to this additional carbonaceous material to reduce the necessary compression of the cathode mass, dominated by the coke.

Preferably, the carbonaceous material is present in amounts, based on the total amount of coke and carbonaceous material, from 1 to 40 wt.%, in particular from 5 to 30 wt.%.

Preferably, in addition to the amount of coke and optionally carbon-containing material that together make up 100 wt.%, can peck added in an amount of from 5 to 40 wt.%, in particular 15 to 30 wt.% (based on 100 wt.% from General�th be processing the mixture). Peck acts as a binder and serves to form a non-deformable bodies during carbonization.

Preferred additives may be oil, such as oil, to facilitate extrusion, or stearic acid. They facilitate the mixing of coke and in certain cases other components.

Preferably, the coke in at least one of the two layers, that is, in the first and/or second layer, contains two sorts of coke, which have different characteristics volume changes during carbonization and/or graphitization, and/or cooling. This is likely to lead to an increase in the density of the formed graphite greater than 1.70 g/cm3in particular more 1,71 g/cm3. Thus, depending on the desires and/or needs you can get both one layer or two layers according to the invention with different types of coke. Also, it is possible to set the bulk density and the volumetric ratio of the densities on demand or on request. For example, it is possible that only the first layer according to the invention was made from two grades of coke, and the second layer was made of only one kind of coke, but additionally included TiB2as the solid material. Thanks to this equalized expansion characteristics of both layers, which preferably can increase the service life of the layer.

In known conditions�x may be preferred, to multilayer block contained more than two layers. In this case, according to the invention can be from more than two layers to obtain an arbitrary number of layers, respectively with two varieties of coke, with different characteristics volume changes.

Other preferred embodiments of and improvements of the invention are further explained in one preferred example implementation.

To obtain the cathode block according to the invention the first and second coke pulverized separately, divided into fractions according to grain size and mixed with pitch from about 15-25 wt.%, for example 20 wt.%, TiB2. The weight fraction of the first coke may be, for example, 10 to 20 wt.% or from 40 to 45 wt.% of the total number of coke. The mixture is filled in the form, which essentially corresponds to the subsequent form of cathode blocks and compacted by vibration or compressed on a block-press. Formed subject to the processing of the workpiece is heated to a final temperature in the range from 2300 to 3000°C, for example at 2600 or 2800°C, while flowing the stage of graphitization, and then cooled. The obtained cathode block has a bulk density 1,68 g/cm3and very high wear resistance against molten aluminum and cryolite. Due to the high degree of graphitization heat and electrical conductivity are high. Roentgen�diffractometry [in Russian has not been established loss TiB 2. The wettability of the cathode block liquid aluminium is very good.

Alternative use a single grade of coke. The wettability characteristics of the obtained cathode block is essentially the same good as in the first example implementation. As a thermal and electrical conductivity are in the range close to the ranges in the first example implementation.

In another embodiment of embodiment of coke in the mixture of graphite powder or carbon particles.

All the features contained in the description, the examples and the formula can be used according to the invention in arbitrary combinations. However, the invention is not limited to the above examples, but can also be made with modifications which in this application are not described specifically.

1. A method of producing multi-layer cathode block having at least first and second layers, comprising the steps:
preparation of starting materials containing coke powder and solid material in the form of TiB2and carbonaceous material, if necessary,
mixing of raw materials,
forming the cathode block, wherein the first layer as the source material comprises coke, and the second layer as the source material comprises coke and solid material in the form of TiB2
carbonation, grafitis�tion and cooling of the cathode block, at this stage graphitization is carried out at temperatures ranging from 2300 to 3000°C, in particular from 2400 to 2900°C, and the second layer is obtained with a thickness comprised between 10 and 50%, in particular 15 to 45%, of the total thickness of the cathode block.

2. A method according to claim 1, characterized in that the stage of graphitization is carried out at a heating rate of 90 to 200 K/h and/or at a temperature of from 2300 to 2900°C.

3. A method according to claim 1 or 2, characterized in that the coke contains two varieties of coke that during carbonization and/or graphitization, and/or cooling have different characteristics volume changes.

4. A method according to claim 3, characterized in that the receiving cathode block with a bulk density of above to 1.68 g/cm3in particular above 1,71 g/cm3.

5. A method according to claim 4, characterized in that the cathode block is obtained in the form of a composite of graphite and solid material.

6. A method according to claim 5, characterized in that the first and/or second layer cathode block as the starting material contains at least one additional carbon-containing material.

7. A method according to claim 1, characterized in that the proportion of graphite and/or graphitized carbon relative to total carbon content of at least one layer of the cathode block is at least 60%.

8. A method according to claim 7, characterized in that the proportion of graphite and/or graphitized carbon is at least 80%.



 

Same patents:

FIELD: metallurgy.

SUBSTANCE: method includes charging of the powdered material in the cathode casing of the electrolyser, its levelling using rack, coverage of the charged material by dust isolating film and compaction performed by two stages: preliminary static and final dynamic action by means of the successive movement of the work organs of the static and dynamic compaction along the longitudinal axis of the cathode of the aluminium electrolyser via the resilient gasket made out of at least two layers: bottom preventing extrusion of the powdered material in front along the movement , and top ensuring gasket engagement with the work organ of the static compaction, at that the dynamic action is performed by vibration unit connected with the static treatment unit by means of the resilient elements with possibility of simultaneous movement relatively to the horizontal and vertical axes.

EFFECT: reduced expenses for lining materials and reduced labour costs during their installation.

7 cl, 9 dwg

FIELD: electricity.

SUBSTANCE: electrolysis unit consists of the following: cathode device with a pool with carbon bottom, the pool is formed by carbon blocks enclosed in metallic casing with flame proof and heat-insulating materials arranged between metallic casing and carbon blocks; anode device including carbon anodes connected to anode bus, the anodes are arranged in upper part of bath and absorbed in fused electrolyte; on the carbon hearth along the anode perimeter the pedestals, or the floats resistant to destruction in cryolite aluminous fusions and liquid aluminium are located. The top surface of a pedestal or a float acts higher than a level of cathodic aluminium and a pedestal or floats can be moved and/or replaced if necessary. Pedestals or floats are made of carbon, carbide of silicon, their combination. The top surface of the pedestal or the float is flat, convex, concave, or inclined to the horizon.

EFFECT: decrease of specific power consumption due to reduction of interpolar gap, ohmic resistance and voltage drop in interpolar gap, increase of current output due to increase of hydrodynamic resistance to movement of fusion near the aluminium-electrolyte interface along the anode perimeter and decrease of mixing of fusion and counter reactions of metal with anode gases.

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FIELD: chemistry.

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18 cl

FIELD: electricity.

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FIELD: electricity.

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3 cl, 2 dwg

FIELD: metallurgy.

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EFFECT: improved wear resistance of a cathode pack and simple manufacturing.

16 cl, 1 dwg

FIELD: electricity.

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10 cl, 5 dwg

FIELD: chemistry.

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15 cl, 8 dwg

FIELD: chemistry.

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3 cl, 3 dwg, 2 ex, 2 tbl

FIELD: metallurgy.

SUBSTANCE: method involves introduction of carbon-bearing substrate material to a mould and application onto it of a layer of composite heat-resistant material containing metal boride, sealing of the contents of the mould in the form of a cathode block and annealing of the cathode block; as material of carbon-bearing substrate and the layer of composite heat-resistant material there used are materials having close coefficients of thermal linear expansion and values of sodium expansion and the following particle size distribution: content of fractions in carbon-bearing substrate (-10+0.071) mm - 76±10 wt % and (-0.071+0) mm - 24±10 wt %, content of fractions in the layer of composite heat-resistant material (-10+0.071) mm - 50±30 wt % and (-0.071+0) mm - 30±50 wt %; with that, material of the carbon-bearing substrate is added to a mould pre-heated to the material temperature. The composite heat-resistant material layer in a sealed state is maximum 8.0% of height of the cathode block and contains 20.0-80.0 wt % of metal diboride. Sealing of the cathode block is performed by vibration moulding, and annealing is performed at 1100°C during 5 hours.

EFFECT: improving quality and service life.

3 cl, 3 dwg, 1 tbl

FIELD: metallurgy; graphitic cathodes for production of aluminum.

SUBSTANCE: 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.

EFFECT: the invention ensures increased service life of the graphitic cathode at the expense of increased erosion resistance in the end areas of the cathode.

6 cl, 7 dwg, 1 tbl

FIELD: metallurgy; production of graphitic cathodes.

SUBSTANCE: 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.

EFFECT: the invention ensures an increase of service life of the graphitic cathode.

4 cl, 2 dwg, 1 ex

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

Aluminum cell // 2256009

FIELD: major repair of aluminum cells.

SUBSTANCE: cathode 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.

EFFECT: improved design, simplified works at major repair.

4 dwg

FIELD: formation of protective coatings for carbon containing components of electrolytic cell at aluminum production.

SUBSTANCE: method 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.

EFFECT: improved resistance of carbon containing component against rupture at operation of electrolysis cell.

34 cl, 1 dwg, 4 tbl, 7 ex

FIELD: non-ferrous metallurgy; electrolytic production of aluminum; cathode units of aluminum electrolyzers.

SUBSTANCE: proposed 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.

EFFECT: increased service life; enhanced strength and reliability; saving of lining material; increased useful volume of electrolyzer; increased yield of aluminum.

4 dwg

FIELD: aluminum cells, namely cathode facing for them.

SUBSTANCE: cathode 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.

EFFECT: increased useful life period, improved operational characteristics of cell.

3 cl, 7 dwg, 1 tbl

FIELD: aluminum production electrolyzers of all types.

SUBSTANCE: proposed 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.

EFFECT: increased service life of electrolyzer; increased daily productivity of electrolyzer.

4 cl, 2 dwg, 1 tbl

FIELD: installation of aluminum electrolyzer hearth.

SUBSTANCE: proposed 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.

EFFECT: increased service life of hearth; reduced yield of low-grade metal; reduced power requirements.

3 dwg, 1 ex

FIELD: mounting aluminum electrolyzers at major repair or in capital construction.

SUBSTANCE: current-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.

EFFECT: enhanced efficiency.

4 cl, 4 dwg, 1 tbl

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