废印制电路板在硝酸浸提液中的金属溶出规律

Study on the metals dissolving from waste printed circuit boards by using nitric acid as leaching liquor

以电子元器件脱落为反应终点,研究了摩尔浓度分别为1.11、1.60、2.19、2.73、3.30、4.55 mol/L的硝酸浸提液中废印制电路板上Cu、Sn、Pb、Fe等金属的溶出规律。结果表明:(1)电子元器件脱落时间随硝酸浓度增大而缩短。(2)当硝酸摩尔浓度小于2.73 mol/L时,废印制电路板中Cu几乎不溶出。(3)废印制电路板中Sn和Pb总体随硝酸浓度增大溶出速率加快,反应初期溶出速率都较快,反应后期溶出速率变慢。(4)当硝酸摩尔浓度大于2.73 mol/L时,反应起始Fe迅速溶出达到一个较稳定的值,随着Sn和Pb的耗尽又一次迅速溶出,后一个迅速溶出规律与Cu一致。(5)在硝酸各浓度下,Sn、Pb溶出率一直高于80%且保持很好的一致性。Ni溶出率随着硝酸浓度的增大总体呈直线升高趋势,最终达到95%以上。当硝酸摩尔浓度小于3.30 mol/L时,Cu、Fe、Zn溶出率均为2%~3%;当硝酸摩尔浓度大于3.30 mol/L时,Cu、Fe、Zn溶出率最终分别约为50%、80%和93%。

The nitric acid solutions with different concentration(1.11,1.60,2.19,2.73,3.30,4.55 mol/L) were employed as leachate for leaching metals from the waste printed circuit boards(PCB).The effects of nitric acid concentration on disassembling times of the electric components and dissolving rate of metals were investigated.Results indicated that the metals were apt to dissolve in solution with higher nitric acid concentration;they all dissolved quickly except Cu,which did not dissolve in the leachate when nitric acid concentration was lower than 2.73 mol/L.The dissolving ratios of Sn and Pb were over 80% for all test runs,and they could reach to 95% when the concentration of nitric acid exceeded 2.73 mol/L.For Cu,Fe and Zn,the dissolving ratios were rather low in leachate when nitric acid concentration was lower than 3.30 mol/L.However,the ratios could reach to 50%,80% and 93% when the nitric acid concentration was 4.55 mol/L.