Process for the recovery of values from secondary aluminum dross
AssigneeAluminum Company of America
InventorsDan Yerushalmi, Richard C. Bennett
Life of this patent
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Abstract
A process for recovery of metallic aluminum, sodium and potassium chloride and an aluminum oxide-metallic aluminum product from secondary aluminum dross. A secondary aluminum dross feed is separated by particle size into a first dross portion which is water leached, filtered, evaporated in an evaporator to produce crystallized sodium and potassium chloride salts, magnesium chloride remaining in solution. A purge stream is removed from the evaporator wherein the crystallized salts are separated therefrom. The purge stream is then discharged onto the crystallized salts.
Claims8
In a process for the recovery of metallic aluminum, mixtures of sodium and potassium chlorides, and an aluminum oxide-metallic aluminum product having high aluminum and low chloride contents from secondary aluminum dross, said process including the steps of providing a secondary aluminum dross feed containing aluminum, aluminum oxide and salts, separating the feed dross by particle size into at least a first dross portion and a second dross portion, treating the first dross portion with leach water to dissolve the salt content thereof, wherein the improvement comprises:
- (a) filtering the leached first dross portion to produce a filtrate containing dissolved sodium and potassium chloride salts and magnesium chloride;
- (b) evaporating the filtrate in an evaporator to produce a slurry containing crystallized sodium and potassium chloride salts, wherein the magnesium chloride remains in solution in the slurry;
- (c) removing a purge stream of slurry from the evaporator;
- (d) subjecting the slurry from which the purge stream has been removed to a liquid solid separation step to remove the crystallized sodium and potassium chloride salts therefrom;
- and
- (e) discharging said purge stream onto said crystallized sodium and potassium chloride salts.
A method of separating salts, including potassium, sodium and magnesium chloride salts, from a brine created by treating secondary aluminum dross with leach water, said method comprising:
- (a) evaporating said brine in an evaporator to produce a slurry containing crystallized sodium and potassium chloride salts, wherein magnesium chloride salt remains in solution in the slurry;
- (b) removing a purge stream of said slurry from said evaporator;
- (c) subjecting the slurry from which the purge stream has been removed to a liquid solid separation step to remove the crystallized sodium and potassium chloride salts therefrom;
- and
- (d) discharging said purged slurry onto said crystallized sodium and potassium chloride salts.
Dependencies are inferred from the claim text.