Recovery of copper oxide from e-waste using ashing, size reduction, nitric acid leaching, solvent extraction and stripping-precipitation: Parametric and scaling up studies and fate of scarce metals

Abstract

Copper recovery from electronic waste in the form of copper oxide was investigated using hydrometallurgy-based process. The recovery process involved dismantling of electronic components, their size reduction, ashing at 600 °C for 4 h to disintegrate the polymer matrix to facilitate metal recovery and remove volatiles as pretreatment, followed by nitric acid leaching, solvent extraction of leachate, and precipitation-stripping with oxalic acid to obtain copper oxalate. Controlled calcinations of the oxalate yielded the valuable copper oxide. Copper concentration in e-waste was found to vary with feed size. Maximum copper concentration of 43.1 % (w/w) was found in the size range of 0.5 mm to 0.355 mm. Maximum leaching of copper (98.7 %) occurred at solid to liquid (S/L) ratio (g/mL) of 1:25 using 10 % nitric acid at 60 °C. For an initial leachate concentration of 30 g/L copper, using 10 % v/v LIX 984 N as the extractant at an organic to aqueous (O/A) phase volume ratio of 1.25:1 resulted in quantitative copper extraction in three stages. Oxalic acid (1 M) was used to strip and precipitate the copper extracted resulting in 99.8 % metal recovery. Scale up of the process did not alter the recoveries. The copper oxide obtained was 99.65 % pure with trace impurities of aluminium and iron. This process aims to achieve high copper recovery while addressing environmental concerns and optimizing resource efficiency, offering potential applications in large-scale electronic waste recycling for valuable metal recovery.