Experimental Research On The Recovery Of Copper From The Waste Printed Circuit Board Of Computer

In this paper, technologies for recovering metals from Waste Electrical and Electronic Equipment (WEEE) were reviewed. Advantages and disadvantages of each technology were discussed in details. It was concluded that the hydrometallurgical technology has broad prospect of industrial application because of its virtues such as the recovery of high-purity metals, lower cost and higher returns-ratio of metals. Mineral acid has been used as leachant to leach copper from WEEE in many studies based on the hydrometallurgical technology. However, some other metals were leached out at the same time, resulting in the complication of latter separation and recovery of Cu from leachate. It was impertative to develop an economical, effective and environmental friendly technology for hydrometallurgically recycling Cu from WEEE.Focusing on the Waste Printed Circuit Board of Computer (WPCB), a closed circulation process of"selectively leaching---extraction---raffinate leaching"was designed to hydrometallurgically recover Cu economically and environmental friendly. Set of Experiments were conducted to clarify some questions during the operation of this process which included the Cu leaching efficiency from WPCB using ammonia-ammonium chloride solution as leachant and using hydrogen peroxide as oxidant, the Cu extraction efficiency from leachate taking organic reagent N910 as extractant, as well as the feasibility of recovering Cu from WPCB by the closed circulation technology under the favorably experimental conditions of extraction and stripping.The main experimental results were as follows:(1) The method of using ammonia-ammonium chloride solution as leachant and using hydrogen peroxide as oxidant has very high selectivity and leaching ability for Cu in WPCB. Under the favorably experimental conditions, the maximum dissolution rate of Cu was as high as 98.65%, while the zinc leaching rate was only 8.12%, and the leaching of other metallic elements such as Nickel, cadmium, tin, aluminum and iron was neglectable. This recovery technology should be an environment-friendly and energy-saving recycling technology because the chemicals were nontoxic and low-corrosivity and the operation was simple, convenient and low-cost.(2) The Cu extraction from leachate of WPCB by extractant N910 has the characteristics of fast kenitics, effective separation, easy to stripping, and good stability. Under the best experimental conditions of extraction and stripping, the single-stage extraction efficiency and the single-stage stripping rate was 99.35% and 95.58%, respectively. The extractant N910 was used 8 times in the experiment of"the extraction-stripping". The extraction rate was always more than 99.25%.(3) The experimental results showed that the leaching rate of Cu drops decreasingly with the increase of recycling times of leaching reagent because of both the inevitable loss of and the zinc leaching consumption of leachant in leaching experiment. However, when the leaching reagent was used 10 times, the leaching rate of Cu was still more than 95%. The performance of extractant N910 was very stable after recycling for 10 times, the extraction rate of Cu maintained about 99.31%.The experimental results demostrated that the closed circulation process of"selectively leaching---extraction---raffinate leaching"was practical. A huge profit space exists in the Cu recovery from WPCB using the new technology. This Cu-recovering technology should bring economic and environmental benefits.