Preparation of pure copper metal from nonferrous metal-bearing scrap

Claim 1

IN A CYCLIC PROCESS OF RECOVERING AN AMMONIACAL LIQUOR-SOLUBLE NON-FERROUS METAL AS POWDER OF HIGH PURITY FROM AN AQUEOUS AMMONIACAL METAL SALT LIQUOR, CONTAINING SAID METAL AND OTHER METALS, THE IMPROVEMENT WHICH COMPRISES: AT SUPERATMOSPHERIC PRESSURE AND AT ABOVE ABOUT 250* F., SUBJECTING A PORTIN OF SAID LIQUOR TO CHEMICAL REDUCTION WITH A SULFUR-FREE REDUCING GAS, MAINTAINING THE REDUCING CONDITIONS ONLY FOR SUFFICIENT TIME TO REDUCE NOT MORE THAN SO MUCH OF THE DESIRED METAL AS WILL PRECIPITATE AS POWDER OF HIGH PURITY, COLLECTING SOPRECIPITATED METAL AS PRODUCT; SEPARATELY SUBJECTING A PORITON OF LEACH LIQUOR TO SIMILAR REDUCING CONDITIONS AT A TEMPERATURE AND FOR A TIME SUFFICIENT TO OBTAIN A LESS PURE PRECIPITATE COMPRISING SUBSTANTIALLY THE ENTIRE DISSOLVED CONTENT OF SAID DESIRED METAL, SEPARATING SAID LESS PURE PRECIPITATE FROM RESIDUAL LIQUOR, AND RETURNING COLLECTED LESS-PURE PRECIPITATE FOR RETREATMENT IN A LATER CYCLE, AT LEAST A PART OF SAID OTHER METAL CONTENT IN THE RESIDUAL LIQUOR BEING REMOVED FROM THE CIRCUIT IN EACH CYCLE.