Preparation of pure copper metal from copper-bearing scrap

Claim 1

IN A PROCESS FOR RECOVERING COPPER METAL FROM COPPER-BEARING MATERIAL IN WHICH SAID MATERIAL IS LEACHED WITH AN AQUEOUS AMMONIACAL SOLUTION OF A COPPER SALT AND COPPER IS CHEMICALLY PRECIPITATED FROM LEACH LIQUOR BY THE TREATMENT WITH A REDUCING GAS; THE IMPROVEMENT WHICH COMPRISES: WITHDRAWING LEACH SOLUTION, FROM SUCH TREATMENT, TREATING WITHDRAWN SOLUTION, AT A TEMPERATURE NOT GREATER THAN 125* F., WITH CARBON MONOXIDE IN AN AMOUNT SUFFICIENT TO DISSOLVE THEREIN A QUANTITY EQUIVALENT TO AT LEAST A MAJOR PORTION OF THE COPPER CONTENT OF THE WITHDRAWN LIQUOR, AND HEATING RESULTANT SOLUTION TO ABOVE ABOUT 150* F. UNDER EQUIVALENT PRESSURE FOR SUFFICIENT TIME ONLY TO REDUCE AND PRECIPITATE COPPER IN METALLIC FORM THEREFROM IN AMOUNT NOT EXCEEDING THAT WHICH IS AT LEAST 99.9% PURE.