CA2972640A1 - Cover for an electrolysis cell for producing aluminium - Google Patents
Cover for an electrolysis cell for producing aluminium Download PDFInfo
- Publication number
- CA2972640A1 CA2972640A1 CA2972640A CA2972640A CA2972640A1 CA 2972640 A1 CA2972640 A1 CA 2972640A1 CA 2972640 A CA2972640 A CA 2972640A CA 2972640 A CA2972640 A CA 2972640A CA 2972640 A1 CA2972640 A1 CA 2972640A1
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- Canada
- Prior art keywords
- cover
- central
- electrolysis cell
- sections
- electrolysis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 60
- 239000004411 aluminium Substances 0.000 title claims abstract description 15
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 15
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 15
- 239000000463 material Substances 0.000 claims abstract description 28
- 230000002093 peripheral effect Effects 0.000 claims abstract description 21
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 16
- 230000007797 corrosion Effects 0.000 claims abstract description 8
- 238000005260 corrosion Methods 0.000 claims abstract description 8
- 230000003628 erosive effect Effects 0.000 claims abstract description 7
- 239000000945 filler Substances 0.000 claims abstract description 6
- 239000000126 substance Substances 0.000 claims abstract description 6
- -1 fluorapophyllite Substances 0.000 claims abstract description 4
- 229910000503 Na-aluminosilicate Inorganic materials 0.000 claims abstract description 3
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims abstract description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 claims abstract description 3
- 239000004927 clay Substances 0.000 claims abstract description 3
- 229910052570 clay Inorganic materials 0.000 claims abstract description 3
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 claims abstract description 3
- 229910001635 magnesium fluoride Inorganic materials 0.000 claims abstract description 3
- 229910052664 nepheline Inorganic materials 0.000 claims abstract description 3
- 239000010434 nepheline Substances 0.000 claims abstract description 3
- 239000010450 olivine Substances 0.000 claims abstract description 3
- 229910052609 olivine Inorganic materials 0.000 claims abstract description 3
- 239000000565 sealant Substances 0.000 claims abstract description 3
- 239000000429 sodium aluminium silicate Substances 0.000 claims abstract description 3
- 235000012217 sodium aluminium silicate Nutrition 0.000 claims abstract description 3
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 3
- 229910052596 spinel Inorganic materials 0.000 claims abstract description 3
- 239000011029 spinel Substances 0.000 claims abstract description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000000155 melt Substances 0.000 abstract description 8
- 238000007789 sealing Methods 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 238000009856 non-ferrous metallurgy Methods 0.000 abstract description 2
- 230000009467 reduction Effects 0.000 abstract description 2
- 239000003792 electrolyte Substances 0.000 description 11
- 239000007789 gas Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 239000012071 phase Substances 0.000 description 4
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- UOBPHQJGWSVXFS-UHFFFAOYSA-N [O].[F] Chemical compound [O].[F] UOBPHQJGWSVXFS-UHFFFAOYSA-N 0.000 description 1
- HZEWFHLRYVTOIW-UHFFFAOYSA-N [Ti].[Ni] Chemical compound [Ti].[Ni] HZEWFHLRYVTOIW-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007792 gaseous phase Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910001000 nickel titanium Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000011020 pilot scale process Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229910021487 silica fume Inorganic materials 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
- C25C3/10—External supporting frames or structures
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/22—Collecting emitted gases
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
Abstract
?The invention relates to non-ferrous metallurgy, more particularly to producing aluminium by electrolysis, and even more particularly to a structural element for covering the space above a melt in an electrolysis cell for producing aluminium by the electrolysis of cryolite-alumina melts. In a cover for an electrolysis cell for producing aluminium, which is in contact with a vapour-gas phase when the electrolysis cell is in operation and which is in the form of central and peripheral sections which are moveably arranged relative to each other, the central and peripheral sections are made from a corrosion-resistant and erosion-resistant material which comprises 80.0-99.0 wt% of fluorophlogopite and 20.0-1.0 wt% of a refractory filler. The central sections of the cover may be permanently fixed on each anode rod, and the peripheral sections may be configured as convex panels rigidly and removably fixed on the top surface of a cathode and supported by the central section of the cover. Moreover, the refractory filler may be chosen from the following chemical substances: clay, calcium fluoride, rutile, sodium aluminosilicate, fluorapophyllite, nepheline, olivine, magnesium fluoride, and spinel. The end and side joints of the central and peripheral covers may be coated with a sealant layer in the form of a layer of alumina, and the central section of the cover may be provided with apertures. The use of this invention provides for the hermetic sealing of the cover, the reliability and safety of the structure, and a reduction in energy consumption.
Description
COVER FOR AN ELECTROLYSIS CELL FOR PRODUCING ALUMINIUM
The invention relates to non-ferrous metallurgy, more particularly to producing aluminium by electrolysis, and even more particularly to a structural element for covering the space above a melt in an electrolysis cell for producing aluminium by the electrolysis of cryolite-alumina melts.
The most important factor defining electrolysis cell performance is the hermetic sealing of a cover above a melt. The hermetic sealing of the electrolysis cell cover is directly associated with aluminium production costs because of its impact on heat and energy balance, raw material consumption and environment.
The primary electrolysis cell cover has following main purposes:
1) It provides heat balance,
The invention relates to non-ferrous metallurgy, more particularly to producing aluminium by electrolysis, and even more particularly to a structural element for covering the space above a melt in an electrolysis cell for producing aluminium by the electrolysis of cryolite-alumina melts.
The most important factor defining electrolysis cell performance is the hermetic sealing of a cover above a melt. The hermetic sealing of the electrolysis cell cover is directly associated with aluminium production costs because of its impact on heat and energy balance, raw material consumption and environment.
The primary electrolysis cell cover has following main purposes:
1) It provides heat balance,
2) It minimizes gaseous emissions,
3) It stabilizes operating modes,
4) It minimizes raw material losses.
The surface area of a cryolite-alumina crust for covering the operating space of electrolysis cell having inert anodes is three times more than that of a standard bath. The cryolite-alumina crust cannot hermetically seal the electrolysis cell across such big surface area because of strength, porous structure, occurring chemical reactions and instability of the surface integrity.
Taking into account mentioned above factors, it is required to hermetically seal an electrolysis cell having inert anodes using a primary cover made of a material which is resistant to a corrosive atmosphere and gaseous fluorine-containing compounds, melt droplets and mechanical loads Such cover should ensure lower gas permeability, integrity, heat insulation, and strength. A cover material and a schematic diagram of cover fixturing should be applicable to all types of electrolysis cells.
US Patent 5582695, IPC CO4B 7/32, CO4B 14/04, CO4B 14/02, CO4B 14/30 published on 10.12.1996 is known. The invention relates to structural elements of aluminium electrolysis cells contacting a gaseous phase, in particular, it relates to covers and anode casings. The aim of this patent is, as disclosed in the specification, to address the problem of hermetic sealing of the space between side boards and anodes of an electrolysis cell having a self-baking anode, in particular it is related to the replacement of a current cryolite-alumina cover consisting of a cast-iron (steel) gas-collecting bell and a cryolite-alumina crust with an "artificial" cover. The suggested artificial cover is made as one piece or as a combined piece made of the refractory concrete having following composition: 15-30 wt% of hydraulic concrete, 5-10 wt% of microsilica, 65-80 wt% of alumina.
This solution has the following main drawback:
According to this patent, during operation the cover material contacts with the electrolysis cell gas-vapour phase comprising not only fluorine and sulphur-containing compounds. The cover material of the electrolysis cell has to be corrosion resistant to the electrolysis cell gas-vapour phase containing fluorine and sulfur compounds in the presence of oxidants CO, CO2, 02, HF, which will enable the usage of the cover for electrolysis cells having a Soderberg anode and backed and inert anodes. The suggested material is not totally inert, and during operation, due to material porosity, this material is soaked with electrolyte vapors. When concrete is soaked, crystal and concrete bounds are destructed resulting in product destruction.
In addition, a method for structural electrolysis cell cover from US Patent .1µ12 2006124471 Al, IPC C25C3/14 published on 15.06.2006 is known. The invention relates to structural elements of a cover and a supply system of aluminium electrolysis cells, in particular to the creation of a sealing cover above electrolyte of the aluminium electrolysis cell at low-temperature operation. One of the conditions of the manufacturing technology is the creation of a gel-like layer on the electrolyte surface, which is provided by electrolyte surface isolation with an artificial cover structure of enhanced heat insulation properties.
The electrolysis cell cover consists of a central section arranged in a central space between anodes along the entire length of a bath. The central section of the cover is secured to a gas pipe beam and is fixed against movement, can comprise several sections, the cover movement is not envisaged. Lateral sections of electrolysis cell cover are movable, can be provided in the form of several lateral sections, which are movable independently from each other and from the central cover. The electrolysis cell cover is made from a ceramic material (e.g., alumina).
This solution has the following main drawback:
The central section of the cover is not adapted for changing its own position, and a disassembling method can be performed only with changing operating position of anodes.
Further, alumina suppliers are required to be disassembled prior to disassembling the central section.
Another significant drawback is a cover material:
¨ ceramics - can be damaged when subjected to temperature difference and mechanical damages.
US Patent X22005230265, IPC C25C3/08, B01D59/40, BO1D59/00, C25C3/00, C25C5/04, C25C7/00 published on 20.10.2005 is known. This invention relates to structural elements of aluminium electrolysis cells contacting a vapour-gas phase of an electrolysis cell, in particular to a cover structure of the upper part of electrolysis cells having backed or inert anodes. The aim of this patent is to eliminate heat losses of an electrolysis cell, namely, to reduce heat transfer from a cover to an environment, to reduce heat consumption for dissolution of the cover fallen into a melt, to reduce heat losses by means of heat balance stabilization and maintaining the operation space shape. In this patent, as well as in the previously described solution, an artificial cover for an electrolyte melt is made in the form of sections movable separately.
Because of its technical specs and the number of similar essential features, the known technical solution is selected as the closest analog (prototype).
According to the prototype solution, sections of an "artificial" cover above an electrolyte melt are made in the form suspended structures. Based on their location, covers are peripheral and central. Peripheral cover sections are made in the form of suspended elements movable separately from each other, from the cover central section and from anodes. A
cover section for the electrolysis cell central space is made in the form of the one-piece element or in the form of several sections. The central cover is extended along the entire length of the electrolysis cell;
cover sections are fixed by means of suspended fasteners and are movable with respect to the melt separately from anodes. The central cover structure is provided with operational doors and apertures, thus, allowing for production operations, bath feeding with raw material, and work with an anode assembly. The peripheral and central covers are made so that cover lifting and replacement can be done in compliance with the anode horizontal arrangement, in other words, actions with the cover wouldn't impact the stability of the current load.
Materials resistant to oxygen and fluoride, e.g., ceramics or composite materials of a casing based on the nickel-titanium alloys and a heat insulator are suggested for use as the cover material.
This solution has the following main drawback:
This artificial cover has the same structure and cannot be considered as versatile for usage in electrolysis cells having backed anodes and a Soderberg anode.
The central cover is secured in the way that makes the cover movable independently from anodes; it inhibits replacement of a failured cover without affecting anodes and stability of electrolysis cell operation. Taking into account the cover section material, the need for periodic replacement of cover section arises. Another significant drawback is a cover material:
¨ ceramics - can be damaged when subjected to temperature difference and mechanical damages, ¨ composite material - is subjected to oxidation under the fluorine-oxygen atmosphere.
The object of the invention is to provide a multifunctional sectional artificial cover above electrolyte melt in electrolysis cells having an inert, backed anode and a Soderberg anode, which shows corrosion and erosion resistance to an aggressive vapour-gas environment of electrolysis cells.
The technical effect of the present invention is to provide a hermetically sealed cover, a reliable and safe structure, and a reduction in energy consumption.
Such technical result is achieved by that in a cover for an electrolysis cell for producing aluminium, which is in contact with a vapour-gas phase when the electrolysis cell is in operation and which is in the form of central and peripheral sections which are movably arranged relative to each other, the central and peripheral sections are made of a corrosion and erosion-resistant material which comprises 80.0-99.0 wt% of fluorophlogopite and 20.0-1.0 wt% of a refractory filler.
The central sections of the cover may be permanently fixed on each anode rod, and the peripheral sections may be configured as convex panels rigidly and removably fixed on the top surface of a cathode and supported by the central section of the cover.
Moreover, the refractory filler may be chosen from the following chemical substances: clay, calcium fluoride, rutile, sodium aluminosilicate, fluorapophyllite, nepheline, olivine, magnesium fluoride, and spinel.
The end and side joints of the central and peripheral covers may be coated with a sealant layer in the form of a layer of alumina, and the central section of the cover may be provided with apertures.
The subject matter of the present invention is as follows:
a cover is manufactured in the form of large-sized products in the form of plates (Fig.1).
The cover is arranged above the top surface of the anode so that it doesn't contact with the electrolyte melt and consists of sections. One complete cover section consists of a central section 1 and a peripheral section 2. The central section 1 of the cover is directly fixed on an anode rod by means of protrusions, wherein the distance from the cover surface to the electrolyte melt is selected based on the electrolysis cell type and specifications. This selected distance makes allowance for the likelihood of brief exposure to electrolyte run-ups onto the cover working surface when changing anode-to-cathode distance in the electrolysis cell. Cover central sections are provided with apertures for alumina dispensers arranged in accordance with an electrolysis cell feeding scheme. The peripheral section 2 of the cover is mounted so that one of its sides is supported by the cover central section, and another side is supported by the top surface of the cathode (such as a flange, an edge, a lining). The width of the peripheral section is equal to that of the central section and is a parabola in shape, thus enabling quick cover removal from the bath for technological operations to be performed. In this way, central and peripheral sections of the cover define a cover section for one anode on the blank or front side, and the number of cover sections corresponds to the number of anodes.
Each cover section is movable together with the anode and can change own position separately from neighbor cover sections and neighbor anodes. The electrolysis cell cover permanently contacts the gas-air environment of the electrolysis cell and periodically contacts the electrolyte melt, that is why the cover is manufactured of the corrosion and erosion resistant material, proof to the aggressive vapour-gas environment of electrolysis cells having backed, self-baking, or inert anodes. The used cover material is not soaked and wetted with the cryolite-alumina melt.
For cover manufacturing, fluorophlogopite or alumina slurries can be used. Independent movement of the cover allows for hermetic sealing of the operation space of the electrolysis cell having inert anodes and makes technological operations simple and mobile. Any cover section can be disassembled independently from the others and replaced with a new part.
One of the factors of variance for a fluorophlogopite cover is a chemical composition of an agglomerate in terms of the main component KMg3(Si3A1)010F2*, because the change of material chemical purity results in the change of physical and chemical properties of the material, and consequently, its mechanical strength, heat conductivity, and corrosion and erosion resistance. When fluorophlogopite is used as the cover material, it is required to use the material containing the main component, fluorophlogopite, in the range of 80-99%, which will allow flexible usage of materials for different types of electrolysis cells.
In addition to hermetic sealing, heat insulation of the operation space above a melt in an electrolysis cell, fluorophlogopite ensures melt and aluminium purity. Operational apertures in the central section of the cover allow using the cover for electrolysis cell feeding, cover installation and disassembling, and maintenance operations. To seal the joints of cover sections alumina is used, which is chemically similar to the fluorophlogopite material. Operational through-apertures in the ends of the cover central section in the electrolysis cell center provide removal of the gas-air mixture from the electrolysis cell to a gas removal system.
The procedure for preparation of the electrolysis cell having the claimed cover includes following steps:
Central and peripheral cover sections are produced from the machined blanks.
Then, appropriate apertures are made in the produced sections according to location and position markings in the electrolysis cell. Next, these cover sections are placed on anodes mounted or being mounted in the following sequence: at first, the central section and then the peripheral section. The cover made of fluorophlogopite can be placed in an active electrolysis cell because this material is resistant to thermal shocks.
The electrolysis cell cover according to the suggested solution features improved reliability, provided by not only the corrosion and erosion resistance of a cover material but also by an independent structural feature of the sectional cover allowing access to any part of the electrolysis cell in a short time without significant intervention in the process. In addition, thermal expansion of the cover material is prevented due to the material properties, allowing free movement of the cover along adjacent covers.
The ease of the suggested cover manufacture process is ensured by the processability of the inventive cover material (fluorophlogopite) and the simplicity of a fastening system on an anode rod allowing for section functionality ensured by means of the product strength and the shape of fastening surface and by supporting the central cover.
Recently conducted long-term laboratory and pilot-scale tests of the claimed fluorophlogopite cover according to the suggested technical solution have shown its functional ability and efficiency.
The surface area of a cryolite-alumina crust for covering the operating space of electrolysis cell having inert anodes is three times more than that of a standard bath. The cryolite-alumina crust cannot hermetically seal the electrolysis cell across such big surface area because of strength, porous structure, occurring chemical reactions and instability of the surface integrity.
Taking into account mentioned above factors, it is required to hermetically seal an electrolysis cell having inert anodes using a primary cover made of a material which is resistant to a corrosive atmosphere and gaseous fluorine-containing compounds, melt droplets and mechanical loads Such cover should ensure lower gas permeability, integrity, heat insulation, and strength. A cover material and a schematic diagram of cover fixturing should be applicable to all types of electrolysis cells.
US Patent 5582695, IPC CO4B 7/32, CO4B 14/04, CO4B 14/02, CO4B 14/30 published on 10.12.1996 is known. The invention relates to structural elements of aluminium electrolysis cells contacting a gaseous phase, in particular, it relates to covers and anode casings. The aim of this patent is, as disclosed in the specification, to address the problem of hermetic sealing of the space between side boards and anodes of an electrolysis cell having a self-baking anode, in particular it is related to the replacement of a current cryolite-alumina cover consisting of a cast-iron (steel) gas-collecting bell and a cryolite-alumina crust with an "artificial" cover. The suggested artificial cover is made as one piece or as a combined piece made of the refractory concrete having following composition: 15-30 wt% of hydraulic concrete, 5-10 wt% of microsilica, 65-80 wt% of alumina.
This solution has the following main drawback:
According to this patent, during operation the cover material contacts with the electrolysis cell gas-vapour phase comprising not only fluorine and sulphur-containing compounds. The cover material of the electrolysis cell has to be corrosion resistant to the electrolysis cell gas-vapour phase containing fluorine and sulfur compounds in the presence of oxidants CO, CO2, 02, HF, which will enable the usage of the cover for electrolysis cells having a Soderberg anode and backed and inert anodes. The suggested material is not totally inert, and during operation, due to material porosity, this material is soaked with electrolyte vapors. When concrete is soaked, crystal and concrete bounds are destructed resulting in product destruction.
In addition, a method for structural electrolysis cell cover from US Patent .1µ12 2006124471 Al, IPC C25C3/14 published on 15.06.2006 is known. The invention relates to structural elements of a cover and a supply system of aluminium electrolysis cells, in particular to the creation of a sealing cover above electrolyte of the aluminium electrolysis cell at low-temperature operation. One of the conditions of the manufacturing technology is the creation of a gel-like layer on the electrolyte surface, which is provided by electrolyte surface isolation with an artificial cover structure of enhanced heat insulation properties.
The electrolysis cell cover consists of a central section arranged in a central space between anodes along the entire length of a bath. The central section of the cover is secured to a gas pipe beam and is fixed against movement, can comprise several sections, the cover movement is not envisaged. Lateral sections of electrolysis cell cover are movable, can be provided in the form of several lateral sections, which are movable independently from each other and from the central cover. The electrolysis cell cover is made from a ceramic material (e.g., alumina).
This solution has the following main drawback:
The central section of the cover is not adapted for changing its own position, and a disassembling method can be performed only with changing operating position of anodes.
Further, alumina suppliers are required to be disassembled prior to disassembling the central section.
Another significant drawback is a cover material:
¨ ceramics - can be damaged when subjected to temperature difference and mechanical damages.
US Patent X22005230265, IPC C25C3/08, B01D59/40, BO1D59/00, C25C3/00, C25C5/04, C25C7/00 published on 20.10.2005 is known. This invention relates to structural elements of aluminium electrolysis cells contacting a vapour-gas phase of an electrolysis cell, in particular to a cover structure of the upper part of electrolysis cells having backed or inert anodes. The aim of this patent is to eliminate heat losses of an electrolysis cell, namely, to reduce heat transfer from a cover to an environment, to reduce heat consumption for dissolution of the cover fallen into a melt, to reduce heat losses by means of heat balance stabilization and maintaining the operation space shape. In this patent, as well as in the previously described solution, an artificial cover for an electrolyte melt is made in the form of sections movable separately.
Because of its technical specs and the number of similar essential features, the known technical solution is selected as the closest analog (prototype).
According to the prototype solution, sections of an "artificial" cover above an electrolyte melt are made in the form suspended structures. Based on their location, covers are peripheral and central. Peripheral cover sections are made in the form of suspended elements movable separately from each other, from the cover central section and from anodes. A
cover section for the electrolysis cell central space is made in the form of the one-piece element or in the form of several sections. The central cover is extended along the entire length of the electrolysis cell;
cover sections are fixed by means of suspended fasteners and are movable with respect to the melt separately from anodes. The central cover structure is provided with operational doors and apertures, thus, allowing for production operations, bath feeding with raw material, and work with an anode assembly. The peripheral and central covers are made so that cover lifting and replacement can be done in compliance with the anode horizontal arrangement, in other words, actions with the cover wouldn't impact the stability of the current load.
Materials resistant to oxygen and fluoride, e.g., ceramics or composite materials of a casing based on the nickel-titanium alloys and a heat insulator are suggested for use as the cover material.
This solution has the following main drawback:
This artificial cover has the same structure and cannot be considered as versatile for usage in electrolysis cells having backed anodes and a Soderberg anode.
The central cover is secured in the way that makes the cover movable independently from anodes; it inhibits replacement of a failured cover without affecting anodes and stability of electrolysis cell operation. Taking into account the cover section material, the need for periodic replacement of cover section arises. Another significant drawback is a cover material:
¨ ceramics - can be damaged when subjected to temperature difference and mechanical damages, ¨ composite material - is subjected to oxidation under the fluorine-oxygen atmosphere.
The object of the invention is to provide a multifunctional sectional artificial cover above electrolyte melt in electrolysis cells having an inert, backed anode and a Soderberg anode, which shows corrosion and erosion resistance to an aggressive vapour-gas environment of electrolysis cells.
The technical effect of the present invention is to provide a hermetically sealed cover, a reliable and safe structure, and a reduction in energy consumption.
Such technical result is achieved by that in a cover for an electrolysis cell for producing aluminium, which is in contact with a vapour-gas phase when the electrolysis cell is in operation and which is in the form of central and peripheral sections which are movably arranged relative to each other, the central and peripheral sections are made of a corrosion and erosion-resistant material which comprises 80.0-99.0 wt% of fluorophlogopite and 20.0-1.0 wt% of a refractory filler.
The central sections of the cover may be permanently fixed on each anode rod, and the peripheral sections may be configured as convex panels rigidly and removably fixed on the top surface of a cathode and supported by the central section of the cover.
Moreover, the refractory filler may be chosen from the following chemical substances: clay, calcium fluoride, rutile, sodium aluminosilicate, fluorapophyllite, nepheline, olivine, magnesium fluoride, and spinel.
The end and side joints of the central and peripheral covers may be coated with a sealant layer in the form of a layer of alumina, and the central section of the cover may be provided with apertures.
The subject matter of the present invention is as follows:
a cover is manufactured in the form of large-sized products in the form of plates (Fig.1).
The cover is arranged above the top surface of the anode so that it doesn't contact with the electrolyte melt and consists of sections. One complete cover section consists of a central section 1 and a peripheral section 2. The central section 1 of the cover is directly fixed on an anode rod by means of protrusions, wherein the distance from the cover surface to the electrolyte melt is selected based on the electrolysis cell type and specifications. This selected distance makes allowance for the likelihood of brief exposure to electrolyte run-ups onto the cover working surface when changing anode-to-cathode distance in the electrolysis cell. Cover central sections are provided with apertures for alumina dispensers arranged in accordance with an electrolysis cell feeding scheme. The peripheral section 2 of the cover is mounted so that one of its sides is supported by the cover central section, and another side is supported by the top surface of the cathode (such as a flange, an edge, a lining). The width of the peripheral section is equal to that of the central section and is a parabola in shape, thus enabling quick cover removal from the bath for technological operations to be performed. In this way, central and peripheral sections of the cover define a cover section for one anode on the blank or front side, and the number of cover sections corresponds to the number of anodes.
Each cover section is movable together with the anode and can change own position separately from neighbor cover sections and neighbor anodes. The electrolysis cell cover permanently contacts the gas-air environment of the electrolysis cell and periodically contacts the electrolyte melt, that is why the cover is manufactured of the corrosion and erosion resistant material, proof to the aggressive vapour-gas environment of electrolysis cells having backed, self-baking, or inert anodes. The used cover material is not soaked and wetted with the cryolite-alumina melt.
For cover manufacturing, fluorophlogopite or alumina slurries can be used. Independent movement of the cover allows for hermetic sealing of the operation space of the electrolysis cell having inert anodes and makes technological operations simple and mobile. Any cover section can be disassembled independently from the others and replaced with a new part.
One of the factors of variance for a fluorophlogopite cover is a chemical composition of an agglomerate in terms of the main component KMg3(Si3A1)010F2*, because the change of material chemical purity results in the change of physical and chemical properties of the material, and consequently, its mechanical strength, heat conductivity, and corrosion and erosion resistance. When fluorophlogopite is used as the cover material, it is required to use the material containing the main component, fluorophlogopite, in the range of 80-99%, which will allow flexible usage of materials for different types of electrolysis cells.
In addition to hermetic sealing, heat insulation of the operation space above a melt in an electrolysis cell, fluorophlogopite ensures melt and aluminium purity. Operational apertures in the central section of the cover allow using the cover for electrolysis cell feeding, cover installation and disassembling, and maintenance operations. To seal the joints of cover sections alumina is used, which is chemically similar to the fluorophlogopite material. Operational through-apertures in the ends of the cover central section in the electrolysis cell center provide removal of the gas-air mixture from the electrolysis cell to a gas removal system.
The procedure for preparation of the electrolysis cell having the claimed cover includes following steps:
Central and peripheral cover sections are produced from the machined blanks.
Then, appropriate apertures are made in the produced sections according to location and position markings in the electrolysis cell. Next, these cover sections are placed on anodes mounted or being mounted in the following sequence: at first, the central section and then the peripheral section. The cover made of fluorophlogopite can be placed in an active electrolysis cell because this material is resistant to thermal shocks.
The electrolysis cell cover according to the suggested solution features improved reliability, provided by not only the corrosion and erosion resistance of a cover material but also by an independent structural feature of the sectional cover allowing access to any part of the electrolysis cell in a short time without significant intervention in the process. In addition, thermal expansion of the cover material is prevented due to the material properties, allowing free movement of the cover along adjacent covers.
The ease of the suggested cover manufacture process is ensured by the processability of the inventive cover material (fluorophlogopite) and the simplicity of a fastening system on an anode rod allowing for section functionality ensured by means of the product strength and the shape of fastening surface and by supporting the central cover.
Recently conducted long-term laboratory and pilot-scale tests of the claimed fluorophlogopite cover according to the suggested technical solution have shown its functional ability and efficiency.
Claims (6)
1. A cover for an electrolysis cell for producing aluminium, which is in contact with a vapour-gas phase when the electrolysis cell is in operation and which is in the form of central and peripheral sections which are movably arranged relative to each other, characterized in that the central and peripheral sections are made from a corrosion-resistant and erosion-resistant material which comprises 80.0-99.0 wt% of fluorophlogopite and 20.0-1.0 wt% of a refractory filler.
2. The cover according to claim 1, characterized in that central sections of the cover are permanently fixed on each anode rod.
3. The cover according to claim 1, characterized in that peripheral sections are configured as convex panels rigidly and removably fixed on the top surface of a cathode and supported by the central section of the cover.
4. The cover according to claim 1, characterized in that the refractory filler may be chosen from the following chemical substances: clay, calcium fluoride, rutile, sodium aluminosilicate, fluorapophyllite, nepheline, olivine, magnesium fluoride, and spinel.
5. The cover according to claim 1, characterized in that the end and side joints of the central and peripheral covers are coated with a sealant layer in the form of a layer of alumina.
6. The cover according to claim 1, characterized in that the central section of the cover is provided with apertures.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| RU2014154035 | 2014-12-29 | ||
| RU2014154035/02A RU2582421C1 (en) | 2014-12-29 | 2014-12-29 | Cover of electrolyser for aluminium production |
| PCT/RU2015/000716 WO2016108726A1 (en) | 2014-12-29 | 2015-10-28 | Cover for an electrolysis cell for producing aluminium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2972640A1 true CA2972640A1 (en) | 2016-07-07 |
Family
ID=55794460
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2972640A Abandoned CA2972640A1 (en) | 2014-12-29 | 2015-10-28 | Cover for an electrolysis cell for producing aluminium |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US20170362726A1 (en) |
| EP (1) | EP3241927A4 (en) |
| CN (1) | CN107532318A (en) |
| AU (1) | AU2015372636A1 (en) |
| CA (1) | CA2972640A1 (en) |
| RU (1) | RU2582421C1 (en) |
| WO (1) | WO2016108726A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2698162C2 (en) | 2017-03-01 | 2019-08-22 | Общество с ограниченной ответственностью "Объединенная Компания РУСАЛ Инженерно-технологический центр" | Perforated metal inert anode for aluminium production by molten electrolysis |
Family Cites Families (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU274933A1 (en) * | 1969-04-21 | 1977-12-05 | Sprygin A I | Method of protection of magnesium electrolyzer lining from electrochemical destruction |
| NO172250C (en) * | 1990-05-07 | 1993-06-23 | Elkem Aluminium | DEVICE FOR CLOSING THE ANODETOPE ON A SODER BERGANODEI AN ELECTROLYCLE CELL FOR ALUMINUM PRODUCTION |
| FR2694945B1 (en) * | 1992-08-20 | 1994-10-07 | Pechiney Aluminium | Very high intensity electrolytic cell superstructure for aluminum production. |
| NO180206C (en) * | 1992-11-30 | 1997-03-05 | Elkem Aluminium | Structural parts for aluminum electrolysis cells |
| ES2165682T3 (en) * | 1997-07-08 | 2002-03-16 | Moltech Invent Sa | CELL FOR THE MANUFACTURE OF ALUMINUM BY ELECTROLYSIS. |
| CN2479028Y (en) * | 2001-05-28 | 2002-02-27 | 郑州轻金属研究院沁阳铝电解试验厂 | Drawer-type cell cover plate |
| WO2003102274A1 (en) * | 2002-06-04 | 2003-12-11 | Moltech Invent S.A. | Aluminium electrowinning cell design with movable insulating cover sections |
| US20060124471A1 (en) * | 2002-12-04 | 2006-06-15 | Nguyen Thinh T | Electrolytic cell with improved feed device |
| CN2641063Y (en) * | 2003-06-13 | 2004-09-15 | 沈阳铝镁设计研究院 | A tank side sealing cover plate for electrolytic tank |
| RU2288976C1 (en) * | 2005-05-04 | 2006-12-10 | Общество с ограниченной ответственностью "Инженерно-технологический центр" | Module-type bus arrangement of aluminum producing electrolyzers |
| RU2316618C2 (en) * | 2006-02-16 | 2008-02-10 | Открытое акционерное общество "РУСАЛ ВСЕРОССИЙСКИЙ АЛЮМИНИЕВО-МАГНИЕВЫЙ ИНСТИТУТ" (ОАО "РУСАЛ ВАМИ") | Electrolyzer for producing magnesium and chlorine |
| RU2361017C2 (en) * | 2007-05-23 | 2009-07-10 | Закрытое акционерное общество "УНИХИМТЕК" (ЗАО "УНИХИМТЕК") | Protective composition, composition material on its basis for secondary covering of cell and method of material's manufacturing |
| RU2375504C2 (en) * | 2007-12-11 | 2009-12-10 | Общество с ограниченной ответственностью "Русская инжиниринговая компания" | Covering of aluminium electrolytic cell with self-burnt anode and top current contact jaw |
| CN101280435A (en) * | 2008-05-27 | 2008-10-08 | 东北大学设计研究院（有限公司） | 400kA level energy-saving emission-reduced prebaking aluminum cell |
| CN201358313Y (en) * | 2009-03-09 | 2009-12-09 | 高德金 | Novel aluminum electrolytic cell gas-shield groove cover plate insulating structure |
| WO2012021924A1 (en) * | 2010-08-16 | 2012-02-23 | Aluminium Smelter Developments Pty Ltd | Rodless anode cassette |
| CN201809455U (en) * | 2010-08-18 | 2011-04-27 | 中国铝业股份有限公司 | Sealing device for cover plate of aluminum electrolysis cell |
| CN202000002U (en) * | 2011-03-24 | 2011-10-05 | 运城市关铝设备材料有限公司 | Novel anticorrosion and anti-deformation heat preserving seal groove cover for electrolysis bath |
| CN202246906U (en) * | 2011-09-15 | 2012-05-30 | 高德金 | Non-insulation groove cover plate of aluminum electrolytic cell |
| CN202881410U (en) * | 2012-10-18 | 2013-04-17 | 郑州龙祥铝业有限公司 | Electrolytic cell and device for sealing shell breaking hammer and horizontal cover thereof |
| CN203360593U (en) * | 2013-05-08 | 2013-12-25 | 戴军 | Energy-saving, thermal-insulating and high-strength sealed cell cover of aluminum reduction cell |
| CN203700545U (en) * | 2013-12-05 | 2014-07-09 | 贵州新峰机电设备有限公司 | Hermetical tank hood of insulating electrolytic bath |
| CN203890450U (en) * | 2014-05-22 | 2014-10-22 | 扬州八方机电设备有限公司 | Novel energy-saving cover plate for electrolytic aluminum bath |
| CN204039517U (en) * | 2014-07-01 | 2014-12-24 | 湖州市织里新飞铝业有限公司 | A kind of aluminium cell mulch resistance material device |
| CN204370001U (en) * | 2014-12-24 | 2015-06-03 | 陕西银仕达信息科技有限公司 | Novel heat-preserving energy-saving electrolgtic aluminium groove cover |
-
2014
- 2014-12-29 RU RU2014154035/02A patent/RU2582421C1/en active
-
2015
- 2015-10-28 CN CN201580074469.2A patent/CN107532318A/en active Pending
- 2015-10-28 AU AU2015372636A patent/AU2015372636A1/en not_active Abandoned
- 2015-10-28 WO PCT/RU2015/000716 patent/WO2016108726A1/en not_active Ceased
- 2015-10-28 EP EP15875779.9A patent/EP3241927A4/en not_active Withdrawn
- 2015-10-28 US US15/540,535 patent/US20170362726A1/en not_active Abandoned
- 2015-10-28 CA CA2972640A patent/CA2972640A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| RU2582421C1 (en) | 2016-04-27 |
| AU2015372636A1 (en) | 2017-08-17 |
| US20170362726A1 (en) | 2017-12-21 |
| CN107532318A (en) | 2018-01-02 |
| EP3241927A1 (en) | 2017-11-08 |
| EP3241927A4 (en) | 2018-11-14 |
| WO2016108726A1 (en) | 2016-07-07 |
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