EDDY CURRENT SEPARATION IN NON-FERROUS METAL RECYCLING: MECHANISMS, DESIGN LIMITS, AND INDUSTRIAL SCALE-UP CONSTRAINTS — A CRITICAL REVIEW

Abstract

Eddy Current Separation (ECS) is widely used in recycling flowsheets to recover non-ferrous metals, particularly from municipal solid waste, electronic waste, and metallurgical residues, where increasing regulatory pressure and circular economy targets demand higher material efficiency. This review critically evaluates the physical principles, equipment design, and operational performance of ECS, with an emphasis on interactions among particle properties (size, shape, conductivity), rotor configuration, and process conditions. While laboratory and pilot studies often report high separation efficiencies (>90% for coarse aluminum fractions), industrial performance is frequently constrained by particle heterogeneity, fines generation (<5 mm), and complex feed compositions, leading to significant losses and misclassification. The review identifies key gaps, including the lack of predictive models for multi-material streams, insufficient integration with upstream comminution and downstream sorting technologies, and limited techno-economic assessments. Particular attention is given to scale-up limitations, rotor wear, energy consumption, and the trade-off between recovery and purity. The analysis highlights that ECS should not be treated as a standalone solution but as a tightly coupled unit within integrated recycling systems. Industrial implications include the need for hybrid separation strategies and improved process control to enhance recovery of fine and complex fractions.