Electrolytic removal of magnesium from molten aluminum
AssigneeGeneral Motors Corporation
InventorsNorman E. Howard, Basant L. Tiwari
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Abstract
Method and apparatus for controlling the temperature of a molten salt, electrolytic demagging cell wherein an operating condition of the cell (e.g., current, temperature, etc.) is measured and a cathode immersed in the cell's electrolyte is moved to and fro the aluminum melt in the cell in response to the measured condition to vary the heat input to the cell.
Claims13
In a cell for the electrolytic removal of magnesium from molten aluminum comprising essentially a vessel having a floor for containing molten Mg-contaminated aluminum and a molten salt electrolyte floating atop the aluminum with an interface therebetween, a cathode spaced from said floor, and means for passing electrolyzing current through said aluminum, electrolyte and cathode to electrolytically scavenge said magnesium from said aluminum and deposit it onto said cathode, the improvement comprising said cathode being a non-consumable electrode adapted for submersion in said electrolyte, and an elevator connected to said cathode for displacing said cathode relative to said floor to vary the distance between said cathode and said interface so as to modulate the temperature of the cell.
In a cell for the electrolytic removal of magnesium from molten aluminum comprising essentially a vessel having a floor for containing molten Mg-contaminated aluminum and a molten salt electrolyte floating atop the aluminum with an interface therebetween, a cathode spaced from said floor, and means for passing electrolyzing current through said aluminum, electrolyte and cathode to electrolytically scavenge said magnesium from said aluminum and deposit it onto said cathode, the improvement comprising said cathode being a non-consumable electrode adapted for submersion in said electrolyte, a sensor for sensing an operating condition of the cell, and an elevator responsive to said sensor for automatically displacing said cathode relative to said floor to vary the distance between said cathode and said interface so as to modulate the temperature of the cell.
A method for controlling the temperature of an aluminum demagging cell having a layer of molten salt electrolyte floating atop a layer of molten Mg-contaminated aluminum comprising the steps of:
- positioning a non-consumable cathode in said electrolyte spaced from the interface between said aluminum and said salt by an interelectrode gap;
- passing sufficient electrolyzing current through said aluminum, electrolyte and cathode to scavenge said magnesium from said aluminum and deposit it on said cathode;
- measuring an operating condition of the cell;
- and
- moving said cathode to and fro with respect to said interface in response to said measured condition to add more or less heat energy to said cell so as to maintain said cell in an optimal temperature range.
Dependencies are inferred from the claim text.