Treatment of molten aluminum

Claim 1

IN A PROCESS WHEREIN MOLTEN IMPURE ALUMINUM CONTAINING EUTECTIC IMPURITIES AND MORE THAN ABOUT 99 PERCENT BY WEIGHT OF ALUMINUM IS FRACTIONALLY CRYSTALLIZED TO INITIALLY PLACE IN SOLID FORM AT LEAST A PART OF THE ALUMINUM AS A HIGHER PURITY PRODUCT THEREBY TO EFFECT A CONCENTRATION OF AT LEAST A PART OF THE EUTECTIC IMPURITIES IN THE RESULTING MOTHER LIQUOR FROM WHICH SAID SOLID ALUMINUM OF HIGHER PURITY TENDS TO SETTLE IN THE FORM OF CRYSTALS BY REASON OF THEIR GREATER DENSITY, THE IMPROVEMENT OF OBTAINING FROM SAID IMPURE ALUMINUM ONE SUBSTANTIAL REMELT FRACTION OF AN ALUMINUM PURITY GREATER THAN THAT OF SAID IMPURE ALUMINUM, AT LEAST ONE OTHER REMELT FRACTION AND A MOTHER LIQUOR FRACTION, BY CONTAINING SAID IMPURE ALUMINUM TO FORM A MOLTEN BODY THEREOF HAVING AN UNCONFINED MOLTEN METAL-AIR INTERFACE REMOVING HEAT OF SOLIDIFICATION AT AND THROUGH SAID INTERFACE AT A RATE TO MAINTAIN FORMATION OF ALUMINUM-RICH CRYSTALS IN A ZONE OF CRYSTALLIZATION WHICH IS AT, UNDER AND SUBSTANTIALLY PARALLEL TO SAID INTERFACE WHILE PREVENTING SUBSTANTIAL LOSS OF HEAT AT THE CONTAINED BOUNDARIES OF SAID BODY, AND DURING SAID CRYSTALLIZATION, COMPACTING THE CRYSTALS THUS FORMED AS THEY SETTLE TO THE LOWER REGIONS OF SAID BODY, BY INTERMITTENTLY APPLYING PRESSURE TO THE UPPER AREA OF THE SETTLED CRYSTAL MASS, AT ANY GIVEN APPLICATION THEREOF, OVER AN AREA OF NOT MORE THAN ABOUT ONE-HALF OF SAID UPPER AREA, CONTINUING SAID CRYSTALLIZATION AND SAID CONCURRENT COMPACTION UNTIL A PREDETERMINED PORTION OF THE ORIGINAL MOLTEN BODY HAS BEEN CRYSTALLIZED, THEREAFTER SEPARATING A MAJOR PORTION OF THE MOTHER LIQUOR FROM THE CONFINED BODY AND APPLYING HEAT OVER THE UPPER SURFACE OF THE THUS PRODUCED MASS OF CRYSTALS TO CAUSE A PROGRESSIVELY DOWNWARD REMELTING OF SAID MASS AND, AS SAID REMELTING PROCEEDS, SEPARATING THE REMELTED METAL INTO AT LEAST TWO SUCCESSIVE FRACTIONS.