• Hubau, Agathe

Abstract

Spent Printed circuit boards (PCBs) are today raising attention because they contain almost 35% of metals including precious and strategic metals even at greater concentration than in primary resources (for instance, gold and copper are 25 to 250 times and 20 to 40 times more concentrated in spent PCBs than in ores, respectively). Consequently, spent PCBs are becoming a valuable resource, while the lack of an appropriate treatment could be a cause of environmental pollution. Today, high-grade PCBs are treated by pyrometallurgy to recover precious metals but many strategic metals are lost in the slag during this operation and the energy-cost of such processes is more and more disadvantageous. Therefore, the design of energy-efficient and cost-effective new processes capable to perform efficient metal recovery from PCBs is particularly important. Emerging techniques based on mechanical processes and hydrometallurgy appear as alternative solutions. In particular, biohydrometallurgy could be very promising. In the literature, few studies deal with the use of bioleaching for the treatment of spent PCBs by means of acidophilic microorganisms, which are mainly ferro and sulfo-oxidant. It allows the recovery of different metals such as Cu, Ni, Zn, etc. In the present study, a double-stage continuous bioreactor was designed to bioleach comminuted spent printed circuit boards (PCB) of low and medium grade. This work is performed at IRCP (Chimie ParisTech) and at the BRGM, in partnership with GeoRessources and is funded by the Chair ParisTech Urban Mines, supported by Eco-systemes.

Topics

• impedance spectroscopy
• gold
• copper