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

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.