초록 ▼

A method of recovering gold and palladium from a spent aqueous potassium iodide-iodine etching solution, and regenerating the etching solution for reuse, involves adjusting the spent solution to a strongly basic pH (e.g., 12.5) by the addition of an alkaline compound (e.g., potassium hydroxide) to p

A method of recovering gold and palladium from a spent aqueous potassium iodide-iodine etching solution, and regenerating the etching solution for reuse, involves adjusting the spent solution to a strongly basic pH (e.g., 12.5) by the addition of an alkaline compound (e.g., potassium hydroxide) to precipitate metallic gold from the solution. Metallic palladium is precipitated from the resulting alkaline solution by the addition of a borohydride, (e.g., potassium borohydride). Following removal of the precipitated gold and palladium, the spent alkaline solution is made acidic-to-neutral in pH to change potassium hypoiodite and some potassium iodide in the solution to iodine. The solution then is adjusted back upward to a slightly alkaline pH value (e.g., 9.0), and precipitate is removed at room temperature. Potassium iodide and iodine crystals then are added to the solution, as necessary, to regenerate the solution to substantially its original composition and strength for reuse.

대표청구항 ▼

A method of recovering gold and palladium from an aqueous potassium iodide-iodine etching solution, which comprises: adjusting the etching solution to a strongly basic pH to produce and alkaline solution and to precipitate metallic gold from the etching solution; adding a borohydride compound to the

A method of recovering gold and palladium from an aqueous potassium iodide-iodine etching solution, which comprises: adjusting the etching solution to a strongly basic pH to produce and alkaline solution and to precipitate metallic gold from the etching solution; adding a borohydride compound to the alkaline solution to precipitate palladium from the resulting alkaline solution; and removing the precipitated metallic gold and palladium from the resulting alkaline solution. A method of regenerating an aqueous potassium iodide-iodine etching solution, which comprises: adjusting the etching solution to a strongly basic pH to produce an alkaline solution and to precipitate metallic gold from the etching solution; removing the precipitated gold from the resulting alkaline solution; adjusting the alkaline solution to an acidic-to-neutral pH to change iodine compounds in the solution to iodine; and adding potassium iodide and iodine, as necessary, to the solution to regenerate the etching solution.