Inertial mixing method for mixing together molten metal streams
AssigneeAluminum Company of America
InventorCharles E. Eckert
Life of this patent
Estimating the term…
Abstract
A system is disclosed for efficiently mixing streams of molten metal to form a molten metal alloy while inhibiting oxidation and introduction of impurities such as hydrogen gas into the molten metal which comprises passing a first molten metal stream at a minimum velocity of at least 18 cm/sec into a mixing zone and feeding a second molten metal stream at a lower velocity into the mixing zone through a concentric feed tube around which the first molten metal stream is flowing. The first molten metal stream is maintained in turbulent flow conditions with a Reynolds number of greater than 2100. In a preferred embodiment, the minimum velocity of the first stream is raised before reaching the mixing zone by introducing a non-oxidizing gas into the stream.
Claims19
A method for efficiently mixing streams of molten metal to form a molten metal alloy while inhibiting oxidation and hydrogen gas adsorption in the molten metal which comprises passing a first molten metal stream through a cylinder in a direction generally rectilinear to the axis of said cylinder and at a minimum velocity of at least 18 cm/sec into a mixing zone within said cylinder and feeding a second molten metal stream into the mixing zone through a feed tube concentrically positioned in said cylinder and having an exit port at said mixing zone around which the first molten metal stream is flowing whereby said two molten metal streams are mixed together in a mixing zone which is beneath the surface of said molten metals to minimize either oxidation or the introduction of impurities such as hydrogen into said mixture.
A method for efficiently mixing two streams of molten metal to form a molten metal alloy while inhibiting oxidation and hydrogen gas adsorption in the molten metal which comprises:
- (a) passing a first molten metal stream through a cylinder in a direction generally rectilinear to the axis of said cylinder and at a minimum velocity of at least 18 cm/sec into a mixing zone within said cylinder;
- and
- (b) feeding a second molten metal stream into said mixing zone through a feed tube concentrically positioned in said cylinder and having an exit port at said mixing zone;
- whereby prior to mixing of said molten metal streams in said mixing zone, said first molten metal stream flow in said cylinder in a direction generally parallel to the axis of said centrally positioned feed tube in said cylinder and therefore flows coaxially to the flow of said second molten metal stream within said feed tube to permit mixing of said two molten metal streams in a mixing zone which is beneath the surface of said molten metals whereby the mixing of said molten metal streams is carried out in a manner which will minimize either oxidation or the introduction of impurities such as hydrogen into said mixture.
A method for efficiently mixing a stream of molten aluminum with a stream of a molten metal of a lighter density to form a molten metal alloy while inhibiting oxidation and hydrogen gas adsorption in the molten metal which comprises:
- (a) passing a stream of molten aluminum through a cylinder in a direction generally rectilinear to the axis of said cylinder and at a minimum velocity of at least 18 cm/sec into a mixing zone within said cylinder;
- (b) introducing into said stream of molten aluminum a sufficient amount of a non-oxidizing gas selected from the class consisting of nitrogen, helium, neon, argon, krypton, and xenon to reduce the density of said molten aluminum to approximately the density of said lighter density molten metal;
- and
- (c) feeding a stream of molten metal of lighter density than said molten aluminum into said mixing zone through a feed tube concentrically positioned in said cylinder and having an exit port at said mixing zone;
- whereby prior to mixing of said molten streams in said mixing zone, said stream of molten aluminum flows in said cylinder in a direction generally parallel to the axis of said centrally positioned feed tube in said cylinder and therefore flows coaxially to the flow of said molten metal stream of lighter density within said feed tube to permit mixing of said two molten metal streams in a mixing zone which is beneath the surface of said molten metals whereby the mixing of said molten metal streams is carried out in a manner which will minimize either oxidation or the introduction of impurities such as hydrogen into said mixture.
A method for efficiently mixing a stream of molten metal lithium with a stream of molten aluminum to form a molten lithium/aluminum alloy while inhibiting oxidation and hydrogen gas adsorption in the molten metal alloy which comprises:
- (a) gravity feeding a stream of molten aluminum from a reservoir down through a cylinder attached thereto into a mixing zone within said cylinder at a minimum velocity at the point of entry into said mixing zone of at least 18 cm/sec;
- (b) feeding a molten lithium stream at a lower velocity than the velocity of said molten aluminum stream into the center of said mixing zone through a concentric feed tube within said cylinder around which said molten aluminum stream is flowing whereby said molten lithium is introduced into said molten aluminum stream below the surface of the molten metals;
- and
- (c) bubbling a non-oxidizing gas selected from the class consisting of nitrogen, helium, neon, argon, krypton, and xenon through said molten aluminum at a rate sufficient to reduce the density of said molten aluminum in said mixing zone below that of lithium to inhibit the flow of lithium back to said aluminum reservoir;
- (d) mixing said molten metal streams together in said mixing zone in the absence of oxidizing gases and hydrogen while maintaining a combined stream molten metal flow velocity in excess of 7.5 cm/sec and turbulent flow conditions signified by a Reynolds number in excess of 2100.
A method for efficiently mixing a stream of molten metal lithium with a stream of molten aluminum to form a molten lithium/aluminum alloy while inhibiting oxidation and hydrogen gas adsorption in the molten metal alloy which comprises:
- (a) passing a stream of molten aluminum from a reservoir into a mixing zone at a minimum velocity at the point of entry into said mixing zone of at least 18 cm/sec;
- (b) bubbling a gas through said molten aluminum at a rate sufficient to reduce the density of said molten aluminum in said mixing zone below that of lithium to inhibit the flow of lithium back to said aluminum reservoir;
- (c) feeding a molten lithium stream into the center of said mixing zone through a concentric feed tube around which said molten aluminum stream is flowing;
- and
- (d) mixing said molten metal stream together in said mixing zone while maintaining a combined stream molten metal flow velocity in excess of 7.5 cm/sec and turbulent flow conditions signified by a Reynolds number in excess of 2100.
Dependencies are inferred from the claim text.