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Cell for the electrowinning of aluminium operating with metal-based anodes

a technology of metal-based anodes and electrowinning cells, which is applied in the direction of machining electrodes, electrical-based machining apparatuses, electrodes, etc., can solve the problems of low electrical conductivity, short life, and inability to meet the overall arrangemen

Inactive Publication Date: 2004-07-29
DE NORA VITTORIO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The invention provides an aluminium electrowinning cell that can operate without excessive contamination of the produced aluminium, with high productivity and low contamination of the product aluminium. The cell includes a horizontal carbon cathode bottom with an aluminium-wettable surface coating and a series of metal-based anodes located above the surface of the top layer of aluminium. The cell also includes a foam-based coating on the carbon cathode bottom and the aluminium-filled plates, which improves the electrical contact between the cathode bottom and the plates. The anodes can be made of metal-based alloys or consumable carbon anodes. The reduced anode-cathode distance allows for increased electrolysis current density and stable cell operation with increased aluminium production. The thickness of the plates and the materials used can be as described in the patent text."

Problems solved by technology

However, no overall arrangement has heretofore been proposed which meets up to all the practical requirements for the industrial production of aluminium with low contamination.
Most metal anodes suggested until now, except anodes covered with a protective cerium-based coating, are highly soluble in the electrolyte utilised contaminating the aluminium produced, and have other drawbacks such as low electrical conductivity, short life and high cost.

Method used

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  • Cell for the electrowinning of aluminium operating with metal-based anodes
  • Cell for the electrowinning of aluminium operating with metal-based anodes
  • Cell for the electrowinning of aluminium operating with metal-based anodes

Examples

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example 2

[0066] An aluminium-wettable ceramic structure for use as a cathode plate in a cell according to the invention was made of a mixture of material inert and resistant to molten aluminium, i.e. alumina and titania, and aluminium-wettable material, i.e. copper oxide. The ceramic structure was prepared by coating a polyurethane foam with a slurry of ceramic particles followed by a heat treatment.

[0067] The slurry of ceramic material consisted of a suspension of 40 g particulate Al.sub.2O.sub.3 with an average particle size of 10 to 20 micron, 2.5 g of particulate CuO with a particle size of less than about 45 micron, 2.5 g of particulate TiO.sub.2 with a particle size of less than about 45 micron in a colloidal alumina carrier consisting of 93 g deionised water and 6.6 g colloidal alumina particles with a colloidal particle size of about 10 to 30 nanometer.

[0068] A polyurethane foam having 10 to 20 pores per inch (equivalent to about 4 to 8 pores per centimetre) was dipped into the slurr...

example 3

[0073] An openly porous silicon carbide structure (30 pores per inch which is equivalent to about 12 pores per centimetre) for use as a cathode plate in a cell according to the invention was rendered aluminium-wettable by coating it with a slurry-applied layer.

[0074] The slurry consisted of 75 g surface oxidised iron particles (-325 mesh), 75 g Silica sol Nyacol 830 (a milky aqueous liquid containing 32 weight % colloidal silicon hydroxide that is converted into silica upon heat treatment) and 0.35 g of an aqueous solution containing 15% PVA (polyvinyl alcohol) that was used to adjust the viscosity of the slurry.

[0075] The openly porous structure was dipped onto the slurry and then dried for 30 min. at 60.degree. C. The impregnated porous structure contained 0.278 g / cm.sup.3 of dried slurry including 0.214 g / cm.sup.3 surface oxidised iron particles.

[0076] The resulting structure was aluminium-wettable and suitable to be wetted by aluminium before use or in-situ when used as a cathod...

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Abstract

A cell for the electrowinning of aluminium comprises a horizontal carbon cathode bottom (11) having an aluminium-wettable surface coating (25) and a series of plates (21) made of aluminium-wettable reticulated porous material, typically foams, filled with aluminium and placed flat on the aluminium-wettable surface coating (25). During use, a thin bottom layer of aluminium (22) wets the aluminium-wettable surface coating (25) on top of the cathode bottom (11) and a bottom part of the porous aluminium-filled plates (21). A top layer of aluminium (23) is formed above the porous aluminium-filled plates (21). The cell may be operated with metal anodes (10) possibly protected with a cerium oxyfluoride coating when operated above about 910°-930° C.

Description

[0001] The invention relates to a cell for the electrowinning of aluminium from alumina dissolved in a crustless fluoride-containing molten electrolyte at a temperature below 930.degree. C., as well as the production of aluminium in such cell.[0002] The production of aluminium today utilises cells for the electrolysis of alumina dissolved in cryolite with an excess of approximately 10 weight % aluminium fluoride, operating at a temperature of approximately 950.degree. C., utilising carbon anodes.[0003] Several patents have been filed and many granted concerning anode and cathode materials, shape, cell designs, operating conditions etc., and many solutions to specific problems have been proposed. However, no overall arrangement has heretofore been proposed which meets up to all the practical requirements for the industrial production of aluminium with low contamination.[0004] Most metal anodes suggested until now, except anodes covered with a protective cerium-based coating, are high...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C25C3/08C25C3/06
CPCC25C3/085C25C3/08
Inventor DE NORA, VITTORIO
Owner DE NORA VITTORIO