Dissolution Of Copper from Waste Printed Circuit Boards (PCBs) in Acidic Cupric Chloride Media (H2SO4-CuSO4-NaCl)

Abstract

This study investigated the dissolution of copper from a high-grade waste printed circuit board (PCB) sample in acidic, cupric chloride media (H2SO4-CuSO4-NaCl + Air). The effects of particle size, solids concentration, acidity, temperature, concentrations of cupric ion, chloride and ferrous ion as well as pre-leach calcination were evaluated in agitated reactors. Copper dissolutions of up to 98% were obtained under optimised conditions. The findings revealed that higher solution potential and dissolved oxygen concentrations significantly enhance the dissolution rate, while reducing particle size and solids concentration improved mass transfer efficiency. Calcination as a pretreatment significantly improved the leaching kinetics, with 93% copper dissolutions achieved after 2 hours. Under the best conditions, comparable results were achieved at both bench and pilot scale, demonstrating potential for large-scale application. Overall, copper dissolution is therefore primarily governed by solution potential, dissolved oxygen concentration, particle size, solids concentration, and acidity. PCB heterogeneity affects mass balance accuracy, highlighting the need for homogenisation procedures to ensure consistent and representative results. A key recommendation is the optimisation of solution potential through enhanced oxygen availability, and higher initial cupric ion concentrations which can substantially improve the rate of copper dissolution.