| 摘要 |
PURPOSE:To perform the purifying treatment of a plating bath soln. incorporating gold cyanide quickly with high efficiency, by regulating the pH of the plating bath soln. to specified value and pressurizing this soln. and passing it through a reverse osmosis membrane. CONSTITUTION:A plating bath soln. incorporating recovered gold cyanide is transferred to a raw liquid tank 1 and the pH is regulated to 4-7. This plating bath is pressurized at about 25-40kg/cm<2>-G with a high-pressure pump 5 and passed through a reverse osmosis membrane 2 and separated into concentrate 4 and permeated liquid 3 and the concentrate 4 is returned to the raw liquid tank 1, circulated and treated. Further as the reverse osmosis membrane, a cellulose acetate-base membrane and a nylon-base membrane are used. Impurities incorporated in the raw liquid tank 1 are concentrated as the return of the concentrate is repeated and the operation is finished at a point of time wherein the osmotic pressure of the raw liquid is made equal to the operation pressure and permeated liquid 3 is not drawn out. Thereby the purification of the plating bath soln. incorporating gold cyanide is easily performed in a short time and it can be reutilized.
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