Abstract: A method for recovering metals from solutions is described. A particular embodiment of the method concerns recovering copper metal from aqueous solutions containing copper ions, such as ammoniacal circuit-board etching solutions. A working embodiment of the invention includes first treating a solution containing copper ions with a sufficient amount of an acid to obtain a solution pH of from about 1 to less than about 2.5. A reducing metal, such as iron, is then added to the solution to precipitate metal ions as metals. The reducing metal has a mesh size of about 230 or greater. The metal precipitate is recovered from the solution. The method is generally sufficiently efficient to allow discharge of solutions treated according to the method of the invention into public waste waters wherein the solution has less than about 5 ppm, and preferably less than 2 ppm, metal ions.

Abstract: A method for recovering metals from solutions is described. A particular embodiment of the method concerns recovering copper metal from aqueous solutions containing copper ions, such as ammoniacal circuit-board etching solutions. A working embodiment of the invention comprises first treating a solution containing copper ions with a sufficient amount of an acid to obtain a solution pH of from about 1 to less than about 2.5. A reducing metal, such as iron, is then added to the solution to precipitate metal ions as metals. The reducing metal has a mesh size of about 230 or greater. The metal precipitate is recovered from the solution. The method is generally sufficiently efficient to allow discharge of solutions treated according to the method of the invention into public waste waters wherein the solution has less than about 5 ppm, and preferably less than 2 ppm, metal ions.

Abstract: A method for recovering metals from solutions is described. A particular embodiment of the method concerns recovering copper metal. The method comprises first treating a solution containing copper ions with a sufficient amount of an inorganic acid to obtain a solution pH of from about 1.5 to less than about 2.5. A reducing metal, such as iron, is then added to the solution to precipitate metal ions, such as copper ions, as metals. The reducing metal has a mesh size preferably smaller than about 350, and even more preferably at least as small as about 400 mesh. The metal precipitate is recovered from solution.