Carbon article, method of producing carbon article and use thereof
SUBSTANCE: invention relates to a carbon article which is produced by burning a mixture at least containing coke. The coke has low graphitisability. Also disclosed is a method of producing a carbon article, which includes mixing anthracite, graphite and/or low-graphitisability coke or mixtures thereof with at least one binding material selected from a group of oil- or carbon-based binding materials, as well as binding materials based on synthetic polymers and any mixtures of said binding materials and optional additives, endowing the mixture with a given shape, firing the moulded mixture and optional graphitisation of the fired moulded article. The invention discloses use of the carbon article as a cathode block of an aluminium electrolysis cell and a blast-furnace brick.
EFFECT: longer service life of the article, particularly a cathode block.
The present invention relates to a carbon product, to a method for manufacturing carbon product and its use.
Carbon products are used as components in the chemical industry, where they are often exposed to aggressive chemicals and high temperatures. These components have to meet high requirements, and they have a limited service life.
Cathodes made of neprofessionalnoe carbon and graphite, is used, for example, as the bottom lining of aluminium electrolysis cells. These materials combine very good electrical conductivity with high thermal stability and chemical resistance. Graphitized cathodes, in particular, are suitable for modern strong cells due to its superior conductivity. However, these cells, including, for example, cathodes on the basis of anthracite, are subject to strong erosion in the process. Erosion is concentrated at the edges of the cathodes, where the predominant current of high density, resulting in the development of W-shaped profile. Mechanical effects also play a significant role, because the layer of molten aluminum at the cathode surface is in constant motion due to strong magnetic fields. Additionally, and chemical�climate impact due to the components of the electrolytic bath. Both types of erosion limits the lifetime of cathode blocks and, thus, of the cell.
The cathode, which should resolve these issues, described in FR 2821365. The cathode comprises a carbon product, which reacts with the sodium even after treatment at temperatures above 2400°C. the Sodium comes from the cryolite, which, as a rule, added to the electrolytic bath.
Refractory blocks for blast furnaces is also made from non-graphitic carbon or graphite. Erosion blocks for blast furnaces mainly occurs in the area of the outlet of the furnace is a technical problem of blast furnaces for iron production. Here, in particular, molten crude iron excessively affects graphite and carbon lining chemically as well as mechanically.
Thus, there is the problem that the carbon product is subject to chemical and mechanical erosion, which naturally reduces its lifespan.
Therefore, the present invention is to offer a carbon product that has a long service life.
According to the present invention, this task is solved carbon article according to claim 1 of the formula of the invention and the method according to claim 10 of the formula of invention.
According to the present invention proposed a carbon product, �izgotavlivaem by firing a mixture which contains, at least, coke, and the coke is a coke with a low graphicelement.
Coke with low graphicelement has high hardness and abrasion resistance even after exposure to high temperature in the production process, which is, for example, up to 3000°C. by the addition of coke with low graphicelement abrasion resistance of the surface carbon of the product is increased compared to traditional carbon products without adding coke with low graphicelement according to the present invention. Coke with low graphicelement acts, in particular, as a means of imparting high abrasion resistance.
Coke with low graphicelement preferably imparts increased bulk density carbon product compared to traditional carbon products.
This preferably coke is a coke with a spherical morphology. Thanks to its approximately spherical geometry coke increases the flowability of the mass for forming carbon products. Thus, the carbon product mainly has a higher bulk density than conventional carbon products. Thus, the carbon product preferably also has high durability.
In addition to coke, which� has a low graphicelement, according to the present invention, the carbon product is preferably produced by using charcoal, graphite and/or coke, for example, petroleum coke or coal pitch coke, at least one binder material, for example, from the group of binder materials, petroleum-based or coal based, such as tar, petroleum pitch, coal tar pitch, bitumen, phenolic resin or furan resin, and optional additives such as carbon fiber. The source of the materials listed above, may contain grains of different sizes. Known compositions containing the above-mentioned starting materials, carbon products, for example, cathode block, or for a blast furnace. When using carbon products that traditionally contain petroleum coke and/or coal pitch coke, preferably, at least some portion of petroleum coke and/or coal tar pitch coke is replaced coke with low graphicelement.
In a preferred embodiment of the graphitization degree according to Myra (Maire) and Möhring (Mehring) is a maximum of 0.5 or less after heat treatment of coke with low graphicelement at 2800°C, according to the calculation by the average distance between the layers of c/2. In the process of graphitization of carbon products at the tempo�the atur up to 3000°C the coke forms a graphite structure in a very small or zero degree and, therefore, retains its abrasion resistance and high hardness.
In yet another preferred embodiment of the grain size of coke with low graphicelement more than 0.2 mm and preferably 0.5 mm. If carbon, the product must have a predetermined electrical conductivity, coke with low graphicelement must be present in the carbon product in an amount of not more than 25% relative to the weight of the dry mixture. Preferably, the coke is present in the carbon product in an amount constituting from 10% to 20% by weight relative to the dry weight of the mixture.
Due to its spherical morphology coke with low graphicelement is a molding additive, which can be obtained a higher bulk density carbon products compared to traditional carbon product. In a preferred embodiment of the Cox has the shape from spherical to slightly ellipsoidal. In addition, it preferably has the structure of type onion skins, which corresponds to its low graphicelement. In the context of the present invention, the term "structure type onion skins" means a multilayer structure containing an inner layer with the shape from spherical to ellipsoidal, covered entirely or in part, by IU�Isha least one intermediate layer and one outer layer. The material for making high bulk density and high resistance to abrasion is most preferable is the coke with low graphicelement, high hardness and spherical structure, shaped like onion skins.
Coke with the shape from spherical to ellipsoidal preferably has a ratio of length and diameter of 1 to 10, preferably 1:5 and preferably 1:3. More than the form of coke approaches the spherical structure, the higher the flowability of the mass and the better mechanical properties of carbon products.
Cox used according to the present invention most preferably has high hardness and isotropy, graphicelement from low to zero, low porosity and low specific surface area, component, for example, from 10 to 40 m2/g and preferably from 20 to 30 m2/G. However, the average distance between layers d002coke, which can be determined by x-ray diffraction, is preferably from 0,340 to 0,344 nm (this corresponds to the degree of graphitization from 0.0 to 0.5 in Myra and Mehring), and is not less than 0,339 nm after heat treatment at 2800°C. the Apparent stacking height of Lcis preferably less than 20 nm after heat treatment at 280°C.
Specific representative examples of coke with low graphicelement coke is obtained as a by-product in the production of unsaturated hydrocarbons, particularly acetylene. Coke with low graphicelement used according to the present invention, it is possible to obtain, in particular, from fractions of crude oil or steam cracking residues, which are used for quenching of gas-phase reactions in the synthesis of unsaturated hydrocarbons (acetylene), where the quenching mixture of oil and soot in the installation guide for coking, which is heated to approximately 500°C. Volatile components of oil for sautéing evaporate in the installation for coking, from the bottom of which you can extract the coke. This method is used for fine-grained coke with the structure of onion skins, which has a high purity in addition to the above properties, and also has a low or zero ash content and mineral content.
Cox preferably has a carbon content comprising at least 96 wt.%, and ash content constituting not more than 0.05 wt.% and preferably not more than 0.01 wt%.
Method for the production of acetylene, which get such coke as a by-product, described for example in DE 2947005 A1. In this way coke with low graphicelement described above, receive �W the quenching oil. For the manufacture of the product according to the present invention, petroleum coke, for example, at least partially replace coke with low graphicelement according to the present invention in the traditional composition of the carbon articles containing petroleum coke.
Coke with low graphicelement, in particular, has high purity and low or zero ash content and mineral content. However coke with low graphicelement may also have a higher ash content and mineral content and, consequently, less high purity. The purity of coke depends on the purity of the used extinguishing product (added for termination of the reaction). Coke is usually a solid with a high carbon content in Nagravision condition and is formed in the pyrolysis of the organic material that passes through a liquid or liquid-crystalline state, at least partially during the process of carbonization. Presumably soot particles prevent the development of the unperturbed liquid phases (mesophases) and attach Cox high hardness and low graphicelement. Thus, the coke produced in the process gas quenching, can be gravitationaly only to a low degree by heat treatment at temperatures above 2200°C. After heat treatment at 2800°C �rednee the distance between the layers of c/2, which is determined by x-ray diffraction and interference of d002is 0.34 nm or more, and in the direction c, the crystallite size of Lcis less than 20 nm, and the crystallite size La110is less than 50 nm, preferably less than 40 nm. Cox used according to the present invention most preferably has high hardness and low graphicelement, and the average distance between the layers of c/2 is greater than or equal to 0.34 nm after heat treatment at 2800°C.
Usually made in such a way that the coke contains spherical particles with a size from several micrometers to several millimeters. Coke with low graphicelement used according to the present invention, preferably contains grains larger than 0.2 mm, preferably larger than 0.5 mm. Preferred grain can be obtained, for example, by screening, followed by appropriate fractionation of coke. In a preferred embodiment of the coke with spherical morphology has a specific surface area by BET method, a component of from 20 to 40 m2/G. It has a very low porosity.
Coke with the structure of onion skins can contain at least one additional substance in its structure. One example of this is the introduction of soot particles, such as parts�s, which are necessarily formed during the synthesis of acetylene.
As additions or alternatives to coke obtained in the production of acetylene, the coke from the coking process/flexicoking (Exxon Mobil) can also be used according to the present invention as coke with low graphicelement. The coke produced in the coking process fluid, also has a low graphicelement. In addition, it also has the shape from spherical to ellipsoidal and structure type onion skins. Compared to coke, which is described above and is formed as a by-product in the production of acetylene, this coke has a higher ash content. X-ray data presented above are also applicable to this Cox.
As a Supplement or alternative, the so-called "coke breeze" (in translation from German means approximately "coke waste"), which is formed in the process of "delayed coking unit", can also be used in the present invention as coke with a spherical morphology. In this case, the parameters of the x-ray diffraction data listed above should be altered due to slightly better graphicelement. After processing at a temperature of 2800°C, the average distance between the layers must exceed 0,338 nm, and the crystallite size in the direction c �must be less than 30 nm. Abrasion resistance of graphitized carbon products do not quite reach the level of coke options described above. However, the improved flowability of the mass is also created due to the spherical morphology of the coke, and the result is a carbon product with a high bulk density.
Carbon product preferably is a cathode block. In the case of the cathode blocks there is a difference between amorphous cathode block, graphitized cathode block and a graphite cathode block, depending on the starting material and/or manufacturing process. In a preferred embodiment of the carbon product is a graphitized cathode block. Carbon the product is suitable as a cathode block due to its high resistance to abrasion, hardness and conductivity.
In an alternative embodiment of the carbon product preferably is a graphitized brick blast furnace. The carbon product according to the present invention can withstand thermal and mechanical loads on the brick of blast furnace, particularly a blast furnace brick, which serves as the lining of a blast furnace to produce iron. Molten iron in a blast furnace with t�UD penetrates into these bricks, thus, there is only minor wear bricks.
A method of making carbon articles according to the present invention comprises the steps of mixing anthracite, graphite or regular coke, for example, petroleum coke or coal pitch coke or mixtures thereof, at least one binder material in the oil or coal based and optionally at least one synthetic binder material based on the polymer and any optional mixtures of the above-mentioned binders and optionally further additives and at least one material for producing high bulk density, with the material to create a high bulk density is the coke with a spherical morphology, then the mixture is subjected to molding to give it a predetermined shape, the molded mixture is fired, and then annealed mixture is optionally subjected to graphitization.
In the method according to the present invention use at least one binder material from the group of binder materials on oil or coal based, such as tar, pitch, bitumen or phenolic resin or furan resin.
Additives can be, for example, carbon nanofibers or carbon fiber.
In the method according to the present �the turbine zobretenie source materials which is used for the manufacture of carbon products used in the form of grains corresponding to the desired size (dimensions). The source material can optionally be sieved before use. All the given starting materials are mixed with each other, not necessarily under the influence of temperature and does not necessarily mix. Then the resulting mixture is subjected to molding and compaction. This is the molding and sealing can be realized, for example, by extrusion, pressing or vibration molding, that is, shaking in a vacuum. Then the molded product is calcined. After that, the carbon product can optionally be subjected to graphitization. Then, the carbon product can be processed to obtain the desired size of his final form.
The firing temperature in the variant of implementation without further graphitization of the surface is preferably from 1100°C to 1500°C. If the carbon product was subjected to graphitization, the firing temperature is preferably from 700°C to 1100°C, and the temperature of graphitization is from 2000°C to 3000°C. the Carbon product can be impregnated and burn again before or after the graphitization. The graphitization is preferably carried out according to the method of graphitization of Acheson kiln (Acheson), preferably according to the method of longitudinal graphitizes�and (LWG) Kastner (Castner).
In the method according to the present invention the coke with low graphicelement used in this way, is obtained from the quenching oil, which is used to stop gas-phase reactions in the synthesis of unsaturated hydrocarbons, particularly acetylene (the so-called acetylene coke). Cox preferably has a carbon content comprising at least 96 wt.%, and ash content constituting not more than 0.05 wt.%, preferably not more than 0.01 wt.%. Spheroidal coke from the coking process fluid (flexicoking) is an alternative to Cox from synthesis of acetylene. Another alternative to Cox from synthesis of acetylene is a coke breeze from the process of a delayed coking. Cox two above-mentioned types is a bad gravitationally solid coke, to which is applicable the above x-ray data.
Coke with low graphicelement, which is obtained as a by-product in the production of acetylene, can be used in the method according to the present invention in a form in which it is obtained in the above process, as described in DE 2947005 A1. Alternatively, the coke can be subjected to a preliminary heat treatment before use in the method according to the present invention. Preliminary therm�ical treatment involves calcination, that is, heat treatment of coke at a temperature comprised between 700°C to 1600°C, preferably from 1000°C to 1500°C, preferably from 1100°C to 1300°C, optionally in a reducing atmosphere. This treatment leads, in particular, to the evaporation of water, volatile combustibles, such as hydrocarbons, e.g., methane, carbon monoxide and/or hydrogen.
In a preferred embodiment of the coke with spherical morphology and degree of graphitization by Myra Mering and after heat treatment of coke at 2,800°C, which is 0.5 or less, according to calculation by the average distance between the layers of c/2, use in the method according to the present invention. Coke with a spherical morphology and low graphicelement is a material that creates a high bulk density and high abrasion resistance.
The amount used of coke with spherical morphology is preferably not more than 25%, preferably from 10% to 20% relative to the weight of the dry mixture. It is preferable to use coke with a spherical morphology and grain size greater than 0.2 mm, preferably greater than 0.5 mm.
The carbon product according to the present invention can be widely used. In particular, due to its high bulk density, high strength resistance, high insid�ostoichivisti, chemical inertness and high thermal stability, it is used as a component in machinery, chemical equipment or heat exchangers, for example, in the field of technological processes. In addition, due to its properties as described above, the carbon product according to the present invention is used as an electrode or lining components in the production of substances which are produced in relatively aggressive conditions, for example, when exposed to aggressive chemicals or high temperatures.
In a preferred embodiment of the carbon product according to the present invention is used as a cathode of the unit cell of the electrolytic cell for aluminium production. By replacing part of the conventional oil-or coal pitch coke in traditional cathode block structures with a special almost spherical solid coke, which has a low graphicelement, cathodic get a unit with a higher bulk density compared to traditional cathode block. In addition, the abrasion resistance of the surface of the cathode block is increased in comparison with the strength of traditional surfaces of the cathode block. Due to the higher bulk density and high strength resistance to abrasion of such a cathode capable of easily anti-static and distribute�Yat corrosion during electrolysis for the production of aluminum, due to the influence of chemicals and especially mechanical stresses.
Alternatively, the carbon product is preferably used as brick blast furnace to produce iron. Due to its higher bulk density and high strength resistance compared to a traditional bricks for blast furnaces, carbon product according to the present invention as a brick blast furnace capable of withstanding mechanical stresses and thermal wear. The carbon product according to the present invention is suitable in particular for use in the area of the outlet of the blast furnace for iron production.
In yet another preferred embodiment of the carbon product according to the present invention is used as an electrode in the carbothermic reduction process. For example, the carbon product according to the present invention is used in the carbothermic production of silicon, in which silica is reduced to silicon.
In addition, the carbon product according to the present invention is preferably used as an electrode in an electrothermal processes of recovery or as a lining for glass melting furnace for aluminum production, �Ethan, silicon, iron, iron alloys, phosphor, glass or cement, and also as a tool for molding and/or as a lining for the melting and casting crucibles, as well as gutters and outlet ports in the above-mentioned devices.
The carbon product according to the present invention can also be used as the anode in the electrolytic production of various substances. Examples include anode for fluorine production, which is required for the production of uranium hexafluoride, in particular, the anode for the production of magnesium, sodium, lithium (electrolysis current melt) or anode in the electrolytic production of chlorine and alkali.
Examples of other applications of carbon products according to the present invention include heating the pipe and/or the ring element hot plate, pipe for degassing and/or distribution system for melting non-ferrous metals, seal, diamond tools, tip for high voltage switches, graphite spheres for reactors with granular fuel component in the field of continuous casting, pressure casting, centrifugal casting or casting car wheels, such as, for example, molds, moulds for melting solder or glass, for use in manufacturing semiconductor wafers, glass is cool� - breaking insulators and solder joints.
The carbon product according to the present invention is also used in the field of technological processes. The carbon product according to the present invention can be used as a component of the heat exchanger, for example, for a heat exchanger with tube bundle of the heat exchanger or seals. In addition, the carbon product according to the present invention can be used as columns, for example, for the synthesis of acids, e.g., HCl synthesis, as a protective tube, the sorting plate, tunnel plate, kolpachny plates, liquid distributors, porous reactor, pumping or bursting disc.
1. The carbon product obtained by firing a mixture containing, at least, coke, wherein the coke has a degree of graphitization by Myra and Mehring, component of 0.50 or less after heat treatment of coke at 2,800°C, according to the calculation by the average distance between the layers of C/2, and the size of grains of coke exceeds 0.5 mm.
2. The carbon product according to claim 1, characterized in that the coke has a spherical morphology.
3. The carbon product according to claim 1, characterized in that the coke contained in amount of not more than 25% by weight, preferably from 10% to 20%, relative to the weight of the dry mix.
4. The carbon product according to any one of claims. 1-3, characterized in that the COC� has a structure type onion skins.
5. The carbon product according to any one of claims. 1-3, characterized in that the coke has a specific surface area by the method of WET constituting from 20 to 40 m2/g.
6. The carbon product according to claim 4, characterized in that the coke has a specific surface area by the method of WET constituting from 20 to 40 m2/g.
7. The carbon product according to any one of claims. 1-3, characterized in that it constitutes the cathode block or brick for blast furnace.
8. The carbon product according to claim 7, characterized in that the cathode unit is a graphitized cathode block.
9. Method of obtaining carbon products, including:
a mix of anthracite, graphite and/or coke, or mixtures thereof, at least one binder material from the group of binder materials on oil or coal based, as well as adhesives based on synthetic polymers, and any mixtures of these binders and optional additives,
giving a mixture of a predetermined shape, and
firing the molded mixture, characterized in that the coke has a degree of graphitization by Myra and Mehring, component of 0.50 or less after heat treatment of coke at 2,800°C, according to the calculation by the average distance between the layers of C/2, and the size of grains of coke exceeds 0.5 mm.
10. A method according to claim 9, characterized in that in the mixture before molding and firing administered supplements and/or Fort�created mixture is subjected to graphitization.
11. A method according to claim 9, characterized in that the coke has a spherical morphology.
12. A method according to claim 11, characterized in that the coke with spherical morphology is added in an amount of not more than 25% by weight, preferably from 10% to 20 wt.%, with respect to the dry weight of the mixture.
13. A method according to claim 12, characterized in that the coke with spherical morphology has a structure type onion skins.
14. A method according to claim 13, characterized in that the coke with spherical morphology has a specific surface area by BET method, a component of from 20 to 40 m2/g.
15. Application of carbon products according to any one of claims. 1-8 as the cathode of the unit cell of the electrolytic cell for aluminium production.
16. The use according to claim 15, characterized in that the carbon product produced by the method according to any one of claims. 9-14.
17. Application of carbon products according to any one of claims. 1-8 as a brick blast furnace to produce iron.
18. The use according to claim 17, characterized in that the carbon product produced by the method according to any one of claims. 9-14.
SUBSTANCE: lining comprises a bottom and current-carrying elements made of aluminium, liquid in the upper part contacting melted aluminium and solid in the lower part, and installed so that they pass through the bottom vertically. The bottom is made from taller bottom blocks having projections and shorter bottom blocks, at that the shorter bottom blocks are mounted at the ends of the bottom. 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 current-carrying elements. The current-carrying elements are attached in the lower part to a current-carrying collector shaped as a plate which extends horizontally out of the ends of the bottom blocks and longitudinal sides of the cathode casing. The current-carrying elements are L- or T-shaped. The bottom blocks are made of high-aluminous concrete annealed up to 1200°C or comprised of several layers: a working layer, made of high-aluminous concrete with the thickness equal to 0.4-0.6 of the bottom block thickness, and the secondary layer, made of fireclay castable concrete - the remaining part. Interconnection of the bottom blocks is made of high-aluminous concrete with reduced viscosity or by means of a gluing or cementing composite with the joint thickness of 5-20 mm.
EFFECT: decreased labour intensity at mounting, reduced power consumption and improved operational reliability of the electrolyser.
4 cl, 9 dwg
SUBSTANCE: cathode shell comprises longitudinal and end walls with vertical reinforcement ribs, a bottom, frames, which cover the walls and bottom and flanged sheet. Flanged sheet is fixed rigidly to intermediate ribs installed between frames at longitudinal walls of the shell by means of detachable joints through horizontal pads. The intermediate ribs are made of sheet metal with thickness from 0.3 up to 1 time of the shell wall thickness.
EFFECT: longer service life of the electrolysis unit.
3 cl, 2 dwg
SUBSTANCE: invention relates to a cathode pack for an aluminium electrolytic cell. The cathode pack comprises a layer of composite containing graphite and solid material such TiB2, present with single mode granulometric composition, while d50 amounts to 10 - 20 mcm, in particular to 12 - 18 mcm, preferably to 14 - 16 mcm. Method for the production of a cathode pack with the said characteristics is described as well.
EFFECT: improved wear resistance of a cathode pack and simple manufacturing.
16 cl, 1 dwg
SUBSTANCE: cathode's top is turned towards the electrolytic bath, and the bottom has contacts for current input. Top and bottom parts, at least, on some sections are connected to each other in disconnectable manner using the protective interlayer.
EFFECT: lowering of the cathode cost and optimisation of the cathode operation.
10 cl, 5 dwg
SUBSTANCE: partitions and/or grids, and/or aluminium-moistened open-pore cellular structures from material lass electrically conductive than aluminium are placed under each anode on the bottom surface, perpendicular and/or at angle 45-90° to bottom plane, perpendicular and/or at angle 45-90° to longitudinal axis of cathode rods, which completely of partially prevent horizontal components of cathode current from flowing in aluminium layer.
EFFECT: reduction of horizontal components of currents in melt layer, uniform distribution of current, reduction of inter-pole distance and reduction of electric energy consumption for aluminium production or increase of output by current.
15 cl, 8 dwg
SUBSTANCE: method involves immersing mounted samples of silicon carbide blocks into an electrolyte at aluminium electrolysis temperature and bubbling the electrolyte with carbon dioxide, air or a mixture thereof, moving the samples and comparing the obtained samples with the original samples. After immersion, the samples are held in the electrolyte which is in contact with aluminium at electrolysis temperature, with the controlled area of the sample in the electrolyte. The samples are then raised and held with the controlled area of the sample in a gas phase for not more than 20 minutes. The samples are then moved in the vertical plane while alternately holding the controlled area in the electrolyte and in the gas phase for not more than 10 minutes and the degree of wear thereof is determined from change in the volume of the samples.
EFFECT: shorter time for testing samples of blocks and obtaining visible reduction in cross dimensions of samples of said blocks owing to intensification of the wear process by increasing the rate of wear.
3 cl, 3 dwg, 2 ex, 2 tbl
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
SUBSTANCE: invention relates to a design of a cathode section of an aluminium electrolyser. The cathode section includes a cathode carbon unit, a cathode current-carrying rod with an electrically conducting part from material with high specific electric conductivity, which is installed in an internal cavity of the cathode carbon unit and fixed in it by means of a cast iron cast. The electrically conducting part of the rod is made in the form of an insert of individual elements attached to each other with a gap, which is installed on one or more outer surfaces of the cathode current-carrying rod through a cast iron casting layer. The individual elements of the insert can be of round or rectangular shape or any other type of cross section. Inserts can be installed throughout the length from 10% to 100% of length of the cathode current-carrying rod.
EFFECT: reduction of voltage drop in a cathode unit and low electric contact resistance between a cathode current-carrying rod and an electrically conducting insert with high specific electric conductivity throughout the length of the cathode current-carrying rod.
3 cl, 3 dwg
SUBSTANCE: on hearth surface placed are baffles and/or grates, and/or open-pore cellular structures wetted by aluminium made of material with lower electric conductivity compared with that of aluminium perpendicular and/or at 45°-90° to heart surface, perpendicular and/or at 45°-90° to lengthwise axis of cathode rods preventing partially or completely the flow of horizontal components of cathode currents in aluminium layer along the hearth. Electrolytic cell can operate with consumable or nonconsumable anodes, that is, "inert" anodes.
EFFECT: uniform current distribution, smaller electrode gap, lower power consumption, higher yield.
15 cl, 5 dwg
SUBSTANCE: electrolysis unit includes a cathode device containing a bath provided with a coal bottom and composed of coal blocks enclosed in a metal housing, with refractory and heat-insulating materials arranged between the metal housing, an anode assembly containing coal anodes connected to anode sludge, arranged in upper part of the bath and submerged into molten electrolyte; at the coal bottom, under each of the anodes there located are floats with higher specific electric conductivity in comparison to that of electrolyte, stable to destruction in cryolite-alumina melts and liquid aluminium; with that, upper surface of the float projects above the level of cathode aluminium and the floats can be moved and/or replaced to reduce inter-pole gap between anode and cathode. The floats are made from carbon, or from silicon carbide, or from a mixture of titanium diboride and carbon based on high-temperature binding substance and are covered with titanium diboride. Upper surface of the float is flat, or convex, or concave, or inclined to horizon and has capillaries and/or channels, and/or planes attaching the upper surface of a pedestal to cathode metal.
EFFECT: reduction of specific power consumption.
15 cl, 4 dwg
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
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.
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.
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