Study On The Leaching Of Copper By Ammoniacal Solution From Copper-containing Waste

At present, the renewal and regeneration of electronic products is speeding up, which brings more and more electronic wastes. A large amount of copper-containing sludge will be produced during the producing of printed circuit board (PCB). These copper-containing wastes are threats to the environment, and cause the waste of copper resources, which is an issue that needs to be solved quickly. So, the research on efficient and clean leaching technology of copper is meaningful to decreasing the harm to environment and resource recycling.On the basis of reviewing literatures at home and abroad, this paper investigated technologies of harmless disposal and resource utilization, and analyzed the advantages and shortcomings of existing technologies on the copper resource utilization. Represented by waste PCB and PCB sludge, completely researching on the leaching technology of copper in copper-containing wastes was carried out, and ammoniacal solution system was established. This dissertation included the following contents and conclusions:(1) PCB sludge and waste PCB samples were treated by aqua regia and the mass content of metals in the samples were determined by ICP. The result showed that the mass content of copper in the PCB sludge and waste PCB were 33.5% and 23.4%, respectively. It showed that the mass content of copper was high, and the copper was of high recovery value. So, the research on the leaching technology of copper in copper-containing wastes was of great economic benefit and practical significance.(2) Aiming at the leaching of copper in the PCB sludge, the effect of concentrations of NH3-(NH4)2SO4 and pH, leaching time, liquid/solid ratio and temperature were investigated. The optimum leaching conditions were found when ammonia/ammonium sulfate concentrations:3.0mol/L and 1.5mol/L; leaching time:180min; liquid/solid ratio: 20mL/g; temperature:25℃. Under these conditions, about 97.5% of copper was effectively leached. Then, a leaching application test was carried out, and the relative standard deviation (RSD) was 0.78%, which shows the result was reliable. In the filtration solution, the concentration of copper was 16.3g/L, while concentrations of other metals were little. It showed that the solution after leaching was relatively pure.(3) Aiming at the leaching of copper in the waste PCB, the effect of concentrations of NH3, (NH4)2SO4 and CuSO4, leaching time, liquid/solid ratio and temperature were investigated. The optimum leaching conditions were found when NH3, (NH4)2SO4 and CuSO4 concentrations:4.0mol/L,0.4mol/L and O.lmol/L; leaching time:300min; liquid/solid ratio:10mL/g; temperature:45℃. Under these conditions, about 92.8% of copper was effectively leached. Then, a leaching application test was carried out, and the relative standard deviation (RSD) was 1.71%, which shows the result was reliable. In the filtration solution, the concentration of copper was 16.3g/L, while concentrations of other metals were little. It showed that the solution after leaching was relatively pure.(4) In order to investigate the leaching mechanism better, the leaching kinetics of copper in PCB sludge was analyzed. The result showed that, the process was controlled by mixed kinetics model, and the reaction and diffusion rates were affected by reactants concentrations. The model was The calculated activation energy for leaching was 18.6 kJ/mol.