4. Recent Technologies in Electronic-Waste Management

The electrical and electronic industry generates more than 50 million metric tonnes of Electronic-waste annually from discarded and obsolete equipment. According to the Environmental Protection Agency (EPA), 7 million tonnes of electronic equipment become obsolete each year, making Electronic-waste the most rapidly growing waste stream in the world. Electronic-waste often contains hazardous materials as well as base metals such as zinc, copper and iron that can reach up to 60.2% in Electronic-waste products such as refrigerators, washing machines and TVs. Global legislation and regulations play an important role in Electronic-waste recycling strategies and cover 66% of electronic industry practices; most importantly to be mentioned are waste electrical and electronic equipment (WEEE) directive, restriction of hazardous substances (RoHS) directive and registration, evaluation, authorization and restriction of chemicals (REACH) directive regulations.

Waste electrical and electronic equipment (WEEE) are classified into four categories which are photovoltaic (PV) panels, cathode ray tube (CRT), liquid crystal displays (LCDs) and light-emitting diode (LED) displays, computers and laptops and cell phones. Photovoltaic panels are a common silicon-based electronic equipment with 65% recycling rate. The recycling process starts with glass and aluminium recovery followed by thermal treatment at 650° C. Another category is liquid crystal displays and light-emitting diode displays which consume 70% of global indium production, while its recycling requires manual sorting and separation, solvent extraction and acid leaching, respectively. Additionally, cell phones have the lowest recycling rate due to the complexity of recycling caused by compact design and high production rate. Lithium is considered the most valuable recycling material in cell phones and smart batteries. In terms of viable Electronic-waste thermal treatment, thermal plasma consumes 2 kWh/kg in both pyrometallurgical and hydrometallurgical recycling processes. It plays an important role in the recovery of heavy metals such as silver, gold, lead and copper due to high energy density, gas flux temperature and ionization that increases reactivity.