A New Technology For Production Basic Copper Carbonate From Waste Etching

Printed circuit board (PCB) is an important component of the electronic products, and it developed very fast along with the electronic industries recent years. Etching is a process whereby the unwanted copper foil on a printed circuit board (PCB) is oxidized and then dissolved into a liquid carrier called an etchant. Acid cupric chloride (CuCl₂) or cupric ammonium chloride (Cu(NH₃)_xCl₂) are the most popular etchants. The spent cupric etchant waste contains significant amounts of copper and acid (alkali). Although the pollution index is very high, the spent cupric etchant waste is valuable resource and it has a very high potential to reuse or recycle. Therefore, it has very vital significance to take widely research about the spent cupric etchant, which can treat the precious copper waste environment friendly and convert to reasonable resource. The thesis will use the spent cupric etchant waste to produce basic copper carbonate, which can recycle the valuable metal and conserve the nature resources, protect the environment.In this paper, a brief introduction on the domestic and foreign comprehensive utilization of the spent cupric etchant has been given and various technologies to produce the basic copper carbonate in the resent years haven been elaborated firstly. Based on the above, a new technology has been brought in to produce the basic copper carbonate using the spent cupric etchant as the raw material, the conditions of which are as follows:(1) When using the waste etching for copper oxide, the temperature was between 85℃and 95℃.(2) When leaching copper oxide, the optimum conditions were: a) n(NH₃):n(Cu)= 3:1, b) n(NH₄HCO₃):CuO=1.25:1, c) the reacting time was 2 hours without heating.(3) When distilling ammonia, a) the vacuum degree is 0.06MPa, the temperature was between 80℃and 95℃, and the ammonia should be heated gradually. b) The distill -ing time is 2.5 hours, c) a two stage way was used to absorb the ammonia for reuse. According to the midterm experiment, by using the new technology, the percenta -ge of copper in the basic copper carbonate was 56%, which mean the quality of this pro -duct had reached the export level. And 97% of ammonia could be recycled.