Alcan International Limited

Peter D Waite

Robert Dumont

Ghyslain Dube

Serge Eugene Lavoie

An injector for injecting gas into a molten metal. The injector has a rotor that is rotatable about an axis of rotation, the rotor having a cylindrical projection-free side surface, a bottom surface, and a cavity for receiving molten metal located centrally of the rotor with respect to the axis of rotation. The rotor is provided with a plurality of openings in the side surface spaced around the rotor for ejecting molten metal and gas from the rotor upon rotation of the rotor about the axis of rotation. At least one opening in the bottom surface communicates with the cavity permitting entry of molten metal into the cavity, and a plurality of passages disposed in the rotor interconnect the cavity and the openings in the side surface. A gas passageway introduces gas into molten metal present within the rotor but lacks direct communication with the cavity, and is provided with at least one outlet opening into at least one of the plurality of passages to ensure regular and even gas distribution. The invention also relates to a molten metal degassing apparatus comprising a trough-like container for conveying a molten metal from an inlet to an outlet, and at least one gas injector of the above-mentioned kind.

Injector for gas treatment of molten metals

A method of and apparatus for treating molten metal to achieve effective removal of such unwanted inclusions as gases, alkali metals, entrained solids, and the like. The method comprises continuously introducing molten metal into a container forming a trough or trough section, such as the trough provided between a melting furnace and a casting machine, providing at least one mechanically movable gas dispenser submerged within the metal in the container and introducing a gas into the metal adjacent to the gas disperser in a part of the trough forming a treatment zone such that the gas is broken into smaller bubbles by the gas dispenser and dispersed through the treatment zone. The trough or trough section is such that it exhibits a static to dynamic metal holdup of less than 50%.

Gas treatment of molten metals

A method of and apparatus for treating molten metal to achieve effective removal of such unwanted inclusions as gases, alkali metals, entrained solids, and the like. The method comprises introducing molten metal into a trough, such as the trough provided between a melting furnace and a casting machine, providing at least one mechanically movable gas injector submerged within the metal in the trough and injecting a gas into the metal in a part of the trough forming a treatment zone through the injector(s) to form gas bubbles in the metal while moving the injector(s) mechanically to minimize bubble size and maximize distribution of the gas within the metal. The injectors are preferably rotated and comprise a rotor body having a cylindrical side surface and a bottom surface, at least three openings in the side surface spaced symmetrically around the rotor body, at least one opening in the bottom surface, and at least one internal passageway for gas delivery and an internal structure for interconnecting the openings in the side surface, the openings in the bottom surface and the internal passageway. The internal structure is adapted to cause gas bubbles emanating from the internal passageway to break up into finer bubbles and to cause a metal/gas mixture to issue from the openings in the side surface in a generally horizontal and radial manner.

Apparatus for gas treatment of molten metals

An apparatus and process are described for treating molten metal. The invention comprises: (a) a heated vessel having inlet and outlet means for the continuous flow of molten metal downwardly through the vessel, (b) a perforated plate extending horizontally across the vessel dividing it into an upper treatment section and a lower treatment section, this plate forming an intermediate treatment section, and (c) a device for injecting gas in the form of small discrete bubbles into the metal in the lower treatment section, this device comprising a hollow rotatable shaft extending downwardly through an opening in the plate with drive means coupled to the upper end of the shaft, a vaned rotor fixedly attached to the lower end of the shaft within the lower treatment section, with one or more passageways within the rotor for conducting gas from the interior of the shaft to the metal in the lower treatment section. When the gas is discharged through the rotor and the rotor is rotated, the gas is injected into the metal in the form of small discrete bubbles which are uniformly dispersed within the lower treatment section. In a preferred embodiment of the invention the gas bubbles move from the rotor upwardly and outwardly in a generally conical pattern to be distributed across the bottom of the perforated plate and pass upwardly through the perforations thereof.

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Chicoutimi, Canada

Peter D Waite