Production of High Purity Copper from Bio-Leaching Solutions of Waste Printed Circuit Boards

Abstract

According to the properties of bioleaching solutions of printed circuit boards (PCBs), impurities in the leaching solution were removed by solvent extraction with N902 (2-hydroxy-5-nonylbenzaldoxime), then the purified solution was subjected to electrolyse for the production of metallic copper. The influence of equilibration time, extractant concentration, O/A ratios, pH value on copper(II) extraction and sulphuric acid concentration on copper(II) stripping had been studied. More than 97.45% of copper can be extracted from a typical bioleaching solution of PCBs after copper extraction was carried out using 10% N902 diluted in kerosene at O/A ratio of 1:1. And more than 93.57% of copper can be stripped from the loaded organic stripped at 1:1 phase ratio with 1.8 M H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> in a single stage. Copper plate with purity higher than 99.83% can be obtained after the electrowinning was conducted at a current density of 200-250 A/m <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> at ambient temperature. Results of the present investigation indicated that bioleaching-solvent extraction-electrowinning could be a new cleaner hydrometallurgy route for recovery copper from the PCBs.