Moltech Invent S.a.

Alusuisse-lonza Services Ltd.

Georges Berclaz

Vittorio De Nora

Jean-Jacques R Duruz

Miroslaw Plata

Bertrand Carrupt

Gaynor Johnston

A cell for the electrowinning of aluminium by the electrolysis from an aluminium compound dissolved in a molten electrolyte (), comprises: (I) a plurality of non-carbon anodes (), each anode being suspended in operating in the molten electrolyte by an anode stem () that connects the anode () to a positive current source; and (II) a thermic insulating cover (') which covers the electrolyte () and through which each anode stem () extends from the positive current source to an anode (). The insulating cover (&#x2032;) comprises a plurality of movable sections () that together cover a substantial part of the electrolyte (). Each movable section () covers a corresponding portion of the electrolyte () that is located therebelow and that can be uncovered by moving the corresponding movable section (). The anode stem () of each anode () extends through the insulating cover (&#x2032;) between two movable sections () or between a movable section () and a fixed section (&#x2032;) of the insulating cover (&#x2032;) when the sections () are in a covering position over the electrolyte (). Each movable section () is movable to uncover the corresponding electrolyte portion without interrupting operation of any anode (), for example by tilting, in particular pivoting, or sliding and/or lifting the section ().

Aluminium electrowinning cell design with movable insulating cover sections

A drained cathode cell for the electrowinning of aluminium comprises a cell bottom ( ) arranged to collect product aluminium and thermic insulating sidewalls ( &prime;) lined with a molten electrolyte resistant sidewall lining ( ) which is made of material liable to react with molten aluminium, in particular containing silicon carbide, silicon nitride or boron nitride. The thermic insulating sidewalls ( &prime;) inhibit formation of an electrolyte crust on the lining ( ), whereby the lining ( ) is exposed to molten electrolyte. The cell bottom ( ) has a peripheral surface from which the insulating sidewalls ( &prime;) extend generally vertically to form, with the cell bottom, a trough for containing molten electrolyte and aluminium produced on at least one drained cathode ( ). The peripheral surface of the cell bottom ( ) is arranged to keep the product aluminium from contacting and reacting with the molten electrolyte resistant sidewall lining ( ) above and around the entire peripheral surface.

Aluminium electrowinning cell with sidewalls resistant to molten electrolyte

An electrolytic cell ( ) for the electrowinning of aluminium comprises a plurality of anodes ( ) immersed in a molten electrolyte ( ), each anode ( ) having an oxygen-evolving active surface of open structure facing and spaced by an inter-electrode gap from a cathode ( ); a thermal insulating cover ( ) above the surface ( ) of the molten electrolyte ( ); and an alumina feed device ( ) arranged above the molten electrolyte surface ( ) for spraying and/or blowing alumina ( ) to an area of the molten electrolyte surface ( ), from where the alumina ( ) dissolves as it enters the electrolyte ( ) and alumina-rich electrolyte flows to the inter-electrode gaps where it is electrolysed to produce oxygen gas on the anodes ( ) and aluminium on the cathode ( ).

Method for producing aluminum and electrolytic cell with improved alumina feed device

A method of applying a treating liquid to a porous body ( ), in particular a pre-baked carbon component of an aluminium production cell, such as an anode block, a cathode block or a sidewall. In this method first the body ( ) to be treated is inserted, with its part to be treated facing up, in the treating chamber ( ). At least one sealing member ( ) is then applied to the body so as to isolate a space ( ) in an upper part of the treating chamber ( ) around the part of the body to be treated from a lower part ( ) of the treating chamber around a bottom part of the body which is not to be treated. Next, treating liquid ( ) is supplied to the upper part ( ) of the treating chamber to cover the part of the body to be treated with the treating liquid and applying a vacuum to intake an amount of the treating liquid into pores in the part of the body to be treated. Then the body ( ) is freed from the sealing member(s) ( ), and removed from the treating chamber ( ).

Method and apparatus for applying a treating liquid to a porous body

A cell for the production of aluminium by the electrolysis of an aluminium compound dissolved in a molten electrolyte, in which an outer mechanical structure forming an outer shell ( ) houses therein one or more inner electrically-conductive cathode holder shells or plates ( ) which contain a cathode mass ( ) and is/are connected electrically to the busbar. The cathode mass ( ) has an aluminium-wettable top surface ( ), preferably at a slope forming a drained cathode. The inner cathode holder shell or shells ( ) is/are separated from the outer shell ( ) by an electric and thermic insulation ( ), the cathode holder shell(s) ( ) also serving to distribute current uniformly to the cathode mass ( ). The or each cathode ( ) formed by the cathode holder shell ( ) and cathode mass ( ) is removable from the cell as a unit.

Aluminum production cell and cathode

A drained cathode cell for the electrowinning of aluminium comprises a cell bottom (,) arranged to collect product aluminium and thermic insulating sidewalls (,) lined with a molten electrolyte resistant sidewall lining (,), in particular containing silicon carbide, silicon nitride or boron nitride. The thermic insulating sidewalls (,) inhibit formation of an electrolyte crust on the lining (,), whereby the lining (,) is exposed to molten electrolyte. The cell bottom (,) has a peripheral zone from which the insulating sidewalls (,) extend generally vertically to form, with the cell bottom, a trough for containing molten electrolyte and aluminium produced on at least one drained cathode (,). The peripheral zone of the cell bottom (,) is arranged to keep the product aluminium from contacting and reacting with the molten electrolyte resistant sidewall lining,).

An open-pored body (,), in particular a carbon component of an aluminum production cell, which is to be exposed to oxidizing conditions or chemical attack at high temperatures is treated to protect the body against oxidation or corrosion at high temperature by impregnating the surface of the body at about ambient temperature with a hot non-saturated liquid (,). This liquid contains a treating agent at a temperature above the temperature of the body. The concentration of treating agent in the hot liquid is such that when the liquid is cooled, before it reaches the temperature of the body, the liquid saturates and treating agent precipitates. A pressure differential is applied to cause the liquid to impregnate into the surface pores of the body (,) and precipitate a layer of the treating agent from the liquid inside the body by cooling as it impregnates the pores of the body. The treating solution preferably comprises soluble boron compounds and, when the body is exposed to high temperature oxidizing conditions, the precipitated layer of the treating agent inside the body forms a protective, vitreous layer in the surface pores which protects the body against oxidation.

Method and apparatus for impregnation of porous bodies for protection against oxidation

The casting machine features a mold (10), a deflection plate (66) with a lower surface (80) for guiding cooling water (20) which is sprayed at high pressure and/or a supporting plate with an upper surface for guiding cooling water (20) flowing at low pressure. Both surfaces for guiding the cooling water (20) are made of insulating material. The electromagnetic shield (18, 76) is cooled on the inside at least in the active region. The mold housing (32) is preferably made out of a perforated sheet (34) which has been bent several ways. The active region of the shield is preferably in the form of a U-shaped or V-shaped shielding sheet and features an insert or coating for reducing the magnetic field of the inductor (12) increasingly in the upwards direction. The water-jetted surface (80) for guiding the cooling water is moved continuously backwards and forwards and/or tilted in a given rhythmic manner. As a result the curtain of water (22), which is independent of the electromagnetic shield (18), is moved up and down over the ingot (14) over a height (h).

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Veyras, Switzerland

Georges Berclaz