Alcan International Limited

Alcan Research and Development Limited

Jean-Paul R Huni

Ghyslain Dube

Serge Eugene Lavoie

Wesley D Stevens

Ernest W Dewing

Raman Radha Sood

Jean Perron

Thierry Bourgeois

Vinko Potocnik

Nigel Ian Steward

Francedillaois Tremblay

Richard F Boivin

Sadashiv K Nadkarni

Mukesh K Jain

Frederick W Southam

Charles J Rogers

Martin Dionne

Thomas J Hudson

Robert LeBlanc

Donald W MacMillan

Ethan A Hollingshead

Thomas G Edgeworth

Paul Desclaux

The invention relates to a metal boride precursor mixture comprising a metal oxide and a boric oxide combined in such a manner so as to produce intimately linked clusters wherein the boric oxide is found within the metal oxide. Furthermore, the invention discloses a carbon composite material made with the metal boride precursor mixture and a carbonaceous component. Finally, the invention also teaches the process for preparing the metal boride precursor mixture comprising steps of providing a metal oxide and a boron oxide, mechanically mixing the metal oxide and the boron oxide at a temperature that liquefies the boron oxide and may impregnate the metal oxide to produce an intimately linked cluster of metal oxide and boric oxide.

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The invention relates to a system for cooling and reducing fluoride emissions from a hot, spent anode butt removed from an electrolysis cell. The system comprises an elongated fluidised bed cooling chamber comprising particles of alumina and conveyor means for transporting a hot, spent anode butt through the fluidised bed. A lower air distributor is provided for injecting fluidising air into the chamber to create the fluidised bed and an upper air distributor is provided which is adapted to direct fluidised particles into contact with the top surface of the hot anode butt, whereby the fluidised bed surrounds the hot anode butt and serves to simultaneously uniformly cool the hot anode butt and significantly reduce fluoride emissions from the hot anode butt.

Fluid bed system for cooling hot spent anode butts

A method and apparatus for treating non-ferrous metal drosses in order to recover the free metal contained therein. The dross is heated by a plasma torch in a rotary furnace, preferably to a temperature above 800.degree. C. The plasma heating and rotary motion make it possible to recover metal from the dross without employing the conventional salt bath. This means that the gases exiting the furnace can be treated more easily to remove pollutants and the solid residues can be discarded without risk of causing environmental pollution. By controlling the speed of rotation of the furnace, large dross lumps can be accommodated and so the conventional grinding and screening procedure of the dross can advantageously be eliminated.

Method and apparatus for recovery of non-ferrous metals from dross

Busbar arrangements for aluminum electrolytic cells. In a first aspect, the invention provides at least one generally horizontal collector busbar on each side of the cell and a number of current tapping points along each collector busbar so that current flows along the collector busbar in opposite directions on each side of the taps. This produces changes of sign in the vertical component of the magnetic field acting on the pad in the longitudinal direction and helps to prevent pad instabilities. In a second aspect, the current taps for the collector busbars are vertically disposed so as to convey current well below the level of the metal pad so that adverse magnetic effects caused by further distribution of the current are minimized. In a third aspect, when the cells are arranged in a row, current is conveyed between cells in a round-end under-cell crisscross arrangement with long horizontal runs of the busbars of adjacent cells being positioned close together with currents flowing in opposite directions to counteract adverse magnetic effects. These aspects of the invention allow electrolytic cells to be operated more efficiently and with decreased capital investment costs.

Busbar arrangement for aluminum electrolytic cells

A method and apparatus for treating non-ferrous metal drosses in order to recover the free metal contained therein. The dross is heated by a plasma torch in a rotary furnace, preferably to a temperature above 800.degree. C. The plasma heating and rotary motion make it possible to recover metal from the dross without employing the conventional salt bath. This means that the gases exiting the furnace can be treated more easily to remove pollutants and the soild residues can be discarded without risk of causing environmental pollution. By controlling the speed of rotation of the furnace, large dross lumps can be accommodated and so the conventional grinding and screening procedure of the dross can advantageously be eliminated.

Recovery of non-ferrous metals from dross using plasma torch

Recovery of non-ferrous metals from dross

A method and apparatus for treating non-ferrous metal drosses in order to recover the free metal contained therein. The dross is heated by a plasma torch in a rotary furnace, preferably to a temperature above 800.degree. C. The plasma heating and rotary motion make it possible to recover metal from the dross without employing the conventional salt bath. This means that the gases exiting the furnance can be treated more easily to remove pollutants and the solid residues can be discarded without risk of causing environmental pollution. By controlling the speed of rotation of the furnace, large dross lumps can be accommodated and so the conventional grinding and screening procedure of the dross can advantageously be eliminated.

A process for forming carbides of silicon or metals in fine powder or whisker form. The process comprises forming a substantially uniform and non-agglomerated dispersion of a microfine powder of an oxide of silicon or a carbide-forming metal within a matrix of a polymer, carbonizing the oxide-containing polymer in an inert atmosphere and heating the carbonized product at high temperature to cause the oxide to react with carbon to form a carbide. The polymer must have a molecular weight of at least 10,000, a high carbon yield of at least 30% by weight, and a chemical structure which is infusible or capable of being rendered infusible. The preferred polymers are polyacrylonitrile, cellulose and polyvinyl alcohol, but other polymers with similar characteristics can be employed. The process is relatively inexpensive and gives an extremely finely divided product of high purity.

Process for producing silicon carbide and metal carbides

An aluminium potline comprises rows of reduction cells with the cells arranged transversely in each row. The invention provides an asymmetric arrangement of busbars (1, 1', 2, 2') for conducting current from the upstream collector bars 16 of an aluminium electrolytic reduction cell 10 underneath the cell to the next downstream cell 12 in the row. One or more of the busbars is displaced longitudinally of the cell towards the end facing a magnetically dominating neighboring row of cells. The extent of the displacement is such as to counteract the magnetic field induced by the neighboring row.

Busbar arrangement for aluminium electrolytic cells

A method for controlling the rate of aluminum fluoride addition to a cryolite-based electrolyte of an aluminum electrolytic reduction cell makes use of the known ratio between cell temperature and bath (NaF:AlF.sub.3) ratio. A target temperature is established corresponding to a target bath ratio. The cell temperature is measured at intervals and the rate of AlF.sub.3 addition altered depending on whether the measured temperature is above or below the target temperature. The method is faster than traditional methods involving analysis of electrolyte samples, and is amendable to computer control.

Controlling AlF.sub.3 addition to Al reduction cell electrolyte

An electrolytic reduction cell for the production of molten metal by electrolysis of a molten electrolyte, which is less dense than the molten metal includes a generally rectangular shell, one or more suspended anodes and a floor structure which supports a body of the molten metal. At least one essentially linear baffle member extends transversely of the cell and is formed with restricted flow channels for absorbing energy from the molten metal and to reduce the amplitude of the wave motion in the molten metal. The baffle may be in the form of a single member formed with apertures for metal flow restriction or may be constituted by a number of separate aligned members with metal flow channels between them.

Electrolytic reduction cells

In a apparatus for the production of aluminium a molten alumina slag, containing combined carbon is circulated through one or more alternately arranged relatively low temperature zones where carbon is added to increase the combined carbon content of the slag by reaction with the alumina slag and high temperature zones where aluminium metal is released by reaction of aluminium carbide and alumina in the slag with consequent depletion of the combined carbon content. Alumina is supplied to the slag at one or more locations. The energy to drive the reactions is preferably supplied by resistance heating of the slag particularly in transit from a low temperature zone to a high temperature zone although usually additional energy is supplied to the slag in the return from a high temperature zone to the next low temperature zone. In most instances the aluminium-liberating reaction is carried out in an upwardly inclined passage and the gas evolved is employed to achieve the circulatory movement of the slag. It is a preferred feature to scrub the gas with carbon without admixed alumina to avoid formation of sticky aluminium oxycarbide in the carbon, which is subsequently added as process charge.

Apparatus for the production of aluminium

An electrolytic reduction cell for the production of aluminium has current collector bars running across the floor of the cell unitarily or in separate sections. Deformation of the molten metal/electrolytic bath interface is reduced by leading current out of the collector bars or bar sections at positions remote from their ends by connector bars connected to said positions.

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Kingston, Canada

Jean-Paul R Huni