Separation of zinc and copper

Claim 1

IN TREATING A ZINCIFEROUS AMMONIACAL-AMMONIUM CARBONATE LIQUOR CONTAINING (A) AT LEAST ABOUT 20 GMS. PER LITER OF DISSOLVED ZINC, (B) DISSOLVED COPPER IN AMOUNT AT LEAST EQUAL TO SAID DISSOLVED ZINC BUT LESS THAN ABOUT FOUR TIMES THE AMOUNT OF DISSOLVED ZINC, AND (C) AMOMONIA IN EXCESS OF THAT REQUIRED TO HOLD SAID COPPER AND ZINC IN SOLUTION AT AMBIENT TEMPERATURE AS METAL AMMINE COMPLEXES, BY EVOLVING AMMONIA AND CARBON DIOXIDE THEREFROM, THEREBY SELECTIVELY PRECIPITATING ZINC VALUES WHILE RETAINING COPPER VALUES IN SOLUTION: THE IMPROVEMENT WHICH COMPRISES: HEATING SAID SOLUTION TO A TEMPERATURE OF FROM ABOUT 60* TO ABOUT 95*C., BUT NOT ABOVE THE BOILING POINT, FOR SUFFICIENT TIME TO INITIATE VOLATILLIZATION AMMONIA, CARBON DIOXIDE AND WATER VAPOR THEREFROM; CONTINUING SAID HEATING AND GAS EVOLUTION FOR SUFFICIENT TIME TO EVOLVE SUBSTANTIALLY ALL AMMONIA AND CARBON DIOXIDE NOT ASSOCIATED WITH ZINC AND COPPER IN A METAL COMPLEX AND CAUSE PRECIPITATION OF WHITISH SUBSTANTIALLY COPPER-FREE ZINCIFEROUS SOLIDS; FURTHER CONTINUING SAID HEATING AND GAS EVOLUTION WITH CONCOMITANT PRECIPITATION; DURING SAID GAS EVOLUTION MAINTAINING IN SAID SOLUTION A WATER CONTENT AT LEAST 40% IN EXCESS OF THAT WHICH WOULD OTHERWISE BE PRODUCED BY WATER VAPOR EVOLUTION; STOPPING SAID HEATING AND PRECIPATION PRIOR TO NOTICEABLE CO-PRECIPATION OF COPPERBEARING SOLIDS AND COLLECTING RESULTANT PRECIPITATE IN WHICH ZINC IS SUBSTANTIALLY THE ONLY METAL.