Study On The Separation Process Of Discarded Printed Circuit Borad

Nowadays with the rapid development of social economy, electronic products are frequently upgraded, which continuously brings great pressure to the environmental protection and resource recovery. Discarded printed circuit boards (PCBs), as the main compositions of electronic products, have the double characteristics with harmfulness and resource. Therefore, the research on reuse, recycling and other forms of recovery of discarded PCBs is becoming an increasingly urgent task naturally.In this thesis, discarded PCBs were comminuted and characterized by several analytical techniques to make sure of the composition. On the foundation of traditional mechanical treatment, the separation process of metal and nonmetal in discarded PCBs and the ordered standard boards was studied by chemical swellings.In this experiment, PCBs were immersed in solvent D, solvent F(Solvent D and solvent F are both confected in the lab by ourselves.), ethylenediamine or other seven different solvents to study the effect of chemicals swelling on peel strength between the copper and main boards. Solvent D, solvent F, acetone, and water, were picked out as chemical swelling reagents in the experiment. The monomer liberation degree, the essential comminuting time aiming to get the certain size particles, accumulated yield and the contents of metal in particles with different diameters were all investigated after immersion using these four solvents respectively. It was shown that chemical swelling could significantly reduce the peel strength of metal and main boards, considerablely reduce essential comminuting time, get a constant particle distributing in a short time and improve monomer liberation degree of the particles. The effect of these solvents in turn is solvent D, solvent F, acetone, and water. The longer the time and the higher the temperature, it was more beneficial to decrease steel strength. In the condition of 150℃&3h or 140℃&5h using solvent D to dip PCBs, the copper would fall away from the main boards spontaneously.The disposals of discarded PCBs through the chemical swelling route depicted in the thesis exhibited high separating efficiency between metal and nonmetal boards, which laid foundation for latter sorting processes. In a word, the chemical swelling method is obviously characteristic of easier operation, less pollution, higher energy efficiency and recyclable solvents, which is an environmental benign, economically viable recovery technology with more practicability than traditional mechanical process.