WO2003010363A1 - Pate de brasque pour cuve d'electrolyse de l'aluminium - Google Patents
Pate de brasque pour cuve d'electrolyse de l'aluminium Download PDFInfo
- Publication number
- WO2003010363A1 WO2003010363A1 PCT/FR2002/002631 FR0202631W WO03010363A1 WO 2003010363 A1 WO2003010363 A1 WO 2003010363A1 FR 0202631 W FR0202631 W FR 0202631W WO 03010363 A1 WO03010363 A1 WO 03010363A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- degree
- pot lining
- paste
- paste according
- adhesion
- 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.)
- Ceased
Links
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
Definitions
- the present invention relates to a pot lining paste for aluminum electrolysis tank.
- an electrolytic cell comprises, in a metal box sheathed with refractories, a cathode sole composed of several cathode blocks, made of carbonaceous materials, juxtaposed.
- This assembly constitutes the crucible which, sealed by pot lining, is the transformation seat, under the action of electric current, of the aluminum electrolytic bath. This reaction takes place at a temperature above 950 ° C.
- the pot lining must therefore have specific properties ensuring the absence of infiltration in the crucible.
- the crucible is in contact with molten electrolytic bath and liquid aluminum.
- the molten bath and the metal overheated to around 300 ° C above its melting point, can seep into any opening and thus react with the refractories located under the cathode blocks or with the metal bars ensuring the passage of current .
- the consequences can be very serious and lead to the premature shutdown of the electrolytic cell resulting in huge reconstruction costs and loss of aluminum production capacity.
- the pot lining is densified between the cathode blocks in intervals often called small joints and between the cathode blocks and the side refractories in intervals often called large joints.
- the pot lining paste must have a rheology guaranteeing an aptitude for shaping to allow obtaining a sufficient level of density and this, with the commonly used equipment that are pneumatic pressers and automatic machines.
- the pot lining paste must also wet the surface of the cathode blocks by penetrating the roughness and the surface porosity of the cathode blocks in order to prepare a good bond.
- the pot lining paste must maintain the seal by ensuring good adhesion to the cathode blocks and by having expanded relative to the level. initial after shaping.
- carbonaceous materials for the production of this pot lining. These materials consist of a mixture of so-called dry ingredients or dry materials, that is to say already heat treated generally above 1000 ° C, such as calcined anthracite and / or artificial graphite and / or coke with a carbonaceous binder. This carbonaceous binder is generally based on coal pitch but also sometimes on petroleum or resin pitch.
- Coal pitch commonly used as a carbon binder for its physicochemical properties allowing the desired properties to be obtained for pot lining is a complex chemical mixture of organic compounds, mainly polycyclic aromatic hydrocarbons (B. Zander, G. Collin, "A review of the significance of polycyclic aromatic chemistry for pitch science", Fuel 72,1993, 1281-1285).
- Polycyclic aromatic hydrocarbons (or PAHs) form a group of organic compounds made up of at least two aromatic rings which can be formed during natural and industrial phenomena. The mechanism of their formation from any organic compound containing carbon and hydrogen is very complex and, to date not fully explained, but it is generally accepted as being the result of two main phenomena: pyrolysis or combustion incomplete.
- PAHs identified by the US Environmental Protection Agency and the European Aluminum Association are commonly used to compare carbon binders.
- benzo (a) pyrene or B (a) P, very toxic, is commonly accepted as being a good reference for evaluating the toxicity of a carbon binder.
- coal pitches Unlike petroleum pitches, the production process for coal pitches limits the generation of B (a) P during a subsequent heat treatment.
- the carbon binder therefore contains a significant amount of volatile matter, some of which is released at the shaping temperature.
- this carbonaceous binder will release volatile matter and chemically and structurally transform in order to give the final properties of the product.
- the emissions from pot lining during installation for which operators are in direct contact with the product , but also during cooking, are still the subject of great concern.
- the passage of so-called hot pot lining i.e.
- the pitch obtained by this process has the following values:> 200 ° C and 0.22 g / cm 2 . These properties as well as its chemical composition, very high toluene insolubles content 45% for values commonly between 20 and 30%, indicate a behavior of this type of pitch completely new to the skilled person. Even with significant process adjustments, it is not obvious, for those skilled in the art, to be able to use this type of binder for the manufacture of pot lining for aluminum electrolysis cell.
- the object of the invention is to provide a pot lining dough whose emission toxicity is greatly reduced, when placed in the aluminum electrolysis tank and during baking, while having the characteristics deemed essential. .
- the pot lining that it relates to contains dry matter consisting of particles of calcined anthracite and / or artificial graphite and / or coke and a carbonaceous binder derived mainly from coal tar, having a low content of polyotoxic aromatic hydrocarbons, the paste having a wettability or degree of adhesion to the cathode blocks and a degree of expansion ensuring a good seal of the electrolysis tank.
- the carbon binder contains less than 500 ppm of benzo (a) pyrene.
- the carbonaceous binder comes from the fluxing of a solid coal pitch by oils with low content of benzo (a) pyrene, to obtain the rheology and wetting or degree of adhesion to the cathode blocks required.
- the wettability or degree of adhesion of the pot lining paste to the cathode blocks is such that a force is necessary to break the carbon bond created at the end of the cooking between densified pot lining paste in a crucible. of graphite, 50 mm in diameter and 50 mm in height, and the graphite crucible, this force preferably being greater than 10 kg.
- the degree of volume expansion of the pot lining is positive and greater than 1%.
- the quantity of benzo (a) pyrene emitted is less than 20 ppm.
- this pot lining paste contains from 10 to 20% of carbon binder and from 90 to 80% of particles of calcined anthracite and / or artificial graphite and / or coke.
- the mixture of carbon binder and so-called dry ingredients is carried out in a mixer which can be heated. Manufacturing consists in replacing the usual binders by the binder considered. The viscosity at this stage can be adjusted to modify the shaping temperature of the pot lining.
- the formability is controlled by the shaping of 180 g of dough in a mold 50 mm in diameter using a Fisher Sand Rammer device. Densification is obtained by the energy generated by successive strokes. It is generally accepted that the analysis of the evolution of the density as a function of the number of strokes makes it possible to define an index of aptitude for grooming in number of strokes which characterizes the rheology of the dough. By working at different temperatures this test allows to define the temperature range for a correct shaping of the pot lining.
- the ability of the pot lining to expand during cooking from room temperature to the operating temperature of the electrolytic cell is measured when cold by dimensional change in volume of a sample of 1500 g in diameter 90 mm and height 150 mm densified and baked at 950 ° C in 38 hours.
- the degree of adhesion to cathode blocks is characterized by the force necessary to break the bond created during the cooking of the densified pot lining in a graphite crucible.
- emission measurements are carried out using capture systems either fixed installed near the operation or mobile carried
- the paste according to the invention was used for the construction of a
- the pot lining of the said invention significantly reduces the level of emissions both during shaping and during cooking.
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
Description
Claims
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR01/10028 | 2001-07-26 | ||
| FR0110028A FR2827877B1 (fr) | 2001-07-26 | 2001-07-26 | Pate de brasque pour cuve d'electrolyse de l'aluminium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2003010363A1 true WO2003010363A1 (fr) | 2003-02-06 |
Family
ID=8865961
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/FR2002/002631 Ceased WO2003010363A1 (fr) | 2001-07-26 | 2002-07-23 | Pate de brasque pour cuve d'electrolyse de l'aluminium |
Country Status (2)
| Country | Link |
|---|---|
| FR (1) | FR2827877B1 (fr) |
| WO (1) | WO2003010363A1 (fr) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4307048A (en) * | 1979-01-17 | 1981-12-22 | Sumitomo Aluminium Smelting Company, Limited | Method for lining an aluminum electrolytic cell |
| RU1778140C (ru) * | 1990-07-10 | 1992-11-30 | Всесоюзный научно-исследовательский институт охраны труда и техники безопасности черной металлургии | Способ получени св зующего |
-
2001
- 2001-07-26 FR FR0110028A patent/FR2827877B1/fr not_active Expired - Fee Related
-
2002
- 2002-07-23 WO PCT/FR2002/002631 patent/WO2003010363A1/fr not_active Ceased
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4307048A (en) * | 1979-01-17 | 1981-12-22 | Sumitomo Aluminium Smelting Company, Limited | Method for lining an aluminum electrolytic cell |
| RU1778140C (ru) * | 1990-07-10 | 1992-11-30 | Всесоюзный научно-исследовательский институт охраны труда и техники безопасности черной металлургии | Способ получени св зующего |
Non-Patent Citations (1)
| Title |
|---|
| DATABASE WPI Section Ch Week 199349, Derwent World Patents Index; Class H08, AN 1993-394066, XP002195588 * |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2827877A1 (fr) | 2003-01-31 |
| FR2827877B1 (fr) | 2003-11-14 |
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