Recovery of critical and precious metals from E-Waste

Waste of Electrical and Electronic Equipment (WEEE) is the fastest growing waste stream in Europe. This waste contains a high amount of critical and valuable metals as the rare earths defined critical materials from European Commission (2010) and the precious metals. Exhaust fluorescent lamps are examples of electronic wastes that have important percentages of rare earths elements (REEs). These types of WEEE represent an important secondary source of REEs. Moreover, they are classified as hazardous materials for the presence of mercury and need to be properly handled. Among the most valuable component of WEE there are printed circuit boards (PCBs) for their precious metals content. In the present paper a hydrometallurgical process for the recovery of REEs (yttrium, europium, terbium, gadolinium, lanthanum and cerium) from fluorescent powders and copper, tin, zinc, gold and silver from WPCBs. Hydrometallurgical process for rare earths recovery includes a preliminary roasting, acid dissolution and precipitation of a mixture of REEs oxalates. Alternately, a solvent extraction operation and stripping can be added after dissolution to selective recover rare earths. For the WPCBs treatment, a hydrometallurgical process consisting of two sequential leaching procedures (performed in counter and cross current ways) followed by selective precipitation/reduction of elements of interest from solution has been designed.