Microwave - Assisted Extraction Of Lead - Tin Antimony In Waste Circuit Boards

The rapid development of science and technology has speeded up electronic products replacement rate and exacerbated the electronic waste polluted the environment. The print circuit board not only is the most damage to the environment, also the part of which is the most difficult to recycle. The print circuit board contains a large number of metals, thus resources in it is necessary.First of all, this paper summarizes several common method of recycling waste printed circuit board, they are physical, chemical, biological technology, in addition compares the advantages and disadvantages of three methods,and the range of application. Analyzed elements in the waste printed circuit board by ICP-AES. The result showed:it contains a variety of elements, non metallic elements accounted for 50%, the other is precious metals for example gold, silver, platinum and base metals copper and iron, also contains many heavy metals like lead, tin, antimony, contents were 48.7mg/g,68.2mg/g,0.5mg/g.Recycling waste print circuit board is mainly aimed at recovery of the precious metals and base metals, heavy metals are less. In this study, utilizes microwave heating and combines with oxidation smelting technology, extracts lead, tin, antimony from the waste print circuit board by wet leaching technology. The experiment is divided into oxidative leaching and Na2S leaching, compares with traditional heating methods, microwave can reduce reaction time from several hours to a few minutes if achieve the same metal leaching rate. This is a waste less and energy consumption less method of leaching the lead, tin and antimony from waste print circuit board which is high efficiency, low consumption and environmentally.Oxidizing leaching stage, explored effects of several factors on leaching rate of lead and tin from waste circuit board into the first filtrate, antimony into first filter residue:oxidant and alkali dosage, microwave power and time. Through the single factor experiment and the orthogonal experiment indicated the optimum reaction condition was:mass ratio of oxidant and alkali to metal powder was 3and5, radiation for 6min under microwave power was 800W. The highest leaching rate of Pb, Sb and Sb was 92.37%,94.4% and 89.36%.Na2S leaching stage, explored the solid to liquid ratio and microwave time effected on leaching rate of antimony from first filter residue into second filter. Through single factor and orthogonal experiments showed the optimum reaction condition was:the liquid to solid ratio was 3, heating under microwave for 20s, leaching rate of Sb was the highest, reached 98.62%. Leaching rate of antimony was the product of rate in oxidizing leaching stage and Na2S leaching stage, calculated the leaching rate of antimony was 88.13%.Finally, proper disposed of the three wastes which produced from the experiment, discussed the routes of recycling of three metal products. Summary of experimental results, summarized the content.