A Systematic Selective Disassembly Approach for Waste Electrical and Electronic Equipment (WEEE)

Abstract

Waste Electrical and Electronic Equipment (WEEE) is one of the major waste streams in terms of quantity and toxicity, and a critical step in WEEE end-of-life (EOL) processing is through disassembly. Compared with full disassembly , which is a sub-optimal solution due to its high operational cost, selective disassembly is more economic and practical as only selected parts with recycling potential are considered. In this paper, a systematic selective disassembly approach for handling WEEE with a maximum disassembly profit in accordance with the WEEE and Restriction of Hazardous Substances (ROHS) Directives has been developed. Firstly, a space interference matrix is generated based on the interference relationship between individual components in the 3D CAD model of WEEE. A matrix analysis algorithm is then applied to obtain all the feasible disassembly sequences. Secondly, an evaluation and decision-making method is developed to find out an optimal selective disassembly sequence from the obtained feasible disassembly sequences. The evaluation takes into account the disassembly profit and requirements of the WEEE and ROHS Directives , which regulate on recycling rates of different types of products and removal requirements of (i) hazardous, (ii) heavy, and (iii) high-value components. Thus, an optimal solution is a selective disassembly sequence that can achieve the maximum disassembly profit, while complying with the WEEE and ROHS restrictions based on a brute-force search method. Finally, an industrial case on Changhong Liquid Crystal Display Televisions (LCD-TVs) of the type LC24F4 is used to demonstrate the effectiveness of the developed approach.

Appendix

Notation
$C^{\text{clean }} \left( {{\text{Oper}}_{i} } \right)$	Clean operation cost
$C^{\text{disassembly }} \left( {{\text{Oper}}_{i} } \right)$	Disassembly operation cost
$C^{\text{hazardous}}$	Hazardous components
$C^{\text{heavy}}$	Heavy components
$C^{\text{high - value}}$	High-value components
$C_{i}$	Component element in matrix
$C^{\text{landfill/incinerate }} \left( {{\text{Oper}}_{i} } \right)$	Disposal operation cost
C(${\text{Oper}}_{i}$)	Operation cost
${\text{Comp}}_{i}$	Components
$C^{\text{repair }} \left( {{\text{Oper}}_{i} } \right)$	Repair operation cost
$C^{\text{shredding }} \left( {{\text{Oper}}_{i} } \right)$	Shredding operation cost
$C^{\text{separation }} \left( {{\text{Oper}}_{i} } \right)$	Separation operation cost
$E^{\text{factory}}$	Factory expense
$N^{\text{labor}}$	Worker number
Profit (${\text{Oper}}_{i}$)	Operation profit
$r_{ij}$	Space interference relationship
$r_{ji}^{\text{cyc}}$	Recycling rate of the material
$R_{\text{recycling}}$	Recycling rate
$T^{\text{disassembly }} \left( {{\text{Oper}}_{i} } \right)$	Disassembly operation time
TP	Total profit
V (${\text{Oper}}_{i}$)	Operation value
$w_{ji}$	Recycling weight of the material
$W^{\text{labor}}$	Worker wage
$W_{\text{total}}$	Total weight