Methodological Study and Application on Technology Policies of PCs Recycling in China

Abstract

China faces great challenge on e-waste problems. Lacking of controllable collection system and compatible management measures, advanced recycling technologies and effective technology policies has resulted in out-of-order flow of e-waste and serious environmental pollution during disassembly and recycling. How to constitute scientifically decision-making technical policies of e-waste treatment and disposal becomes a significant topic in terms of constructing a resource saving and environmentally sound society in China. In this paper, waste PCs were selected as the tracer and possible collection routes and recycling methods of waste PCs were designed. A new method of material flow analysis in combination with economic stream analysis of PCs was created and a Monte-Carlo mathematical model of cost minimization in the constraints of environmental sound handling of waste PCs was established. By following the streams of different treatment processes consisting of various technologies from collection, transport, treatment, recycling and disposal of waste PCs, the economic distribution in terms of possibility functions was identified. Every technical step was evaluated economically. The optimal treatment/ disposal technology proposed was the ones with high possibilities in the model calibration results. Results showed that operation life span plays the key role. The model supports the process of maintenance for the short lasting PCs. For the long lasting PCs, following recycling and disposal technologies combinations are recommended: mechanical recycling for waste plastics, electronic wire heater method to separate panel glass and cone glass, panel glass recycling as panel glass raw material, cone glass recycling as cone glass raw material". Results also showed that for waste printed circuit boards, content of noble metals is the key factor for selection of mechanical treatment technology. When Au content is below 1 g/t, "wet shredding + water table separation " is an optimal flowsheet; when Au content is above 1 g/t, "dry shedding +electrostatic separation +centrifugal separation " is the best choice.