The intricate composition of waste printed circuit boards (PCBs) presents a significant challenge for efficient and environmentally benign metal recovery. Conventional recycling methods are often energy-intensive or generate secondary pollutants. This study proposes and optimizes a sustainable physical separation flowsheet integrating thermal pre-treatment with gravity concentration. Waste PCBs were thermally conditioned at 200°C to enhance metal liberation, followed by a Mozley Mineral Separator (MMS) separation of the metallic fraction. A central composite design (CCD) and response surface methodology (RSM) were employed to model and optimize the separation process by varying water flow rate, amplitude, and retention time. Robust quadratic models were developed to predict metallic yield ( R 2 = 0.98) and copper recovery ( R 2 = 0.99). The models successfully quantified the complex, non-linear process dynamics, revealing that both responses decrease with increasing water flow rate and retention time, while exhibiting a distinct parabolic relationship with amplitude. This work provides a validated predictive tool to navigate the fundamental trade-off between concentrate yield and metal recovery, enabling process optimization based on specific economic or technical objectives. This statistically robust approach represents a significant advancement toward the design of efficient, predictable, and environmentally benign physical recycling flowsheets for e-waste valorization.
Haque et al. (Wed,) studied this question.