Thesis Title: Ηydrometallurgical processes for recovery of basic and critical metals from printed circuit boards (PCBs)
Monday 18 February 2019, at: 12:00, Venue: Hall Κ1.117
Examination Committee
- Professor Evangelos Gidarakos (advisor)
- Professor Ioannis Yentekakis
- Assistant Professor Nikolaos Xekoukoulotakis
Abstract
Electrical and electronic waste is one the fastest growing waste streams in the world. They contain amongst others, dangerous metals, and also precious metals such as copper, gold, silver, palladium and platinum. The recovery of metals from electronic waste can lead to significant environmental and economic benefits. However, only 15% of the global e-waste is fully recycled.
Printed circuit boards (PCBs) are one of the main components of electrical and electronic equipment. PCBs are a complex e-waste which contains a multitude of components. The latter consists of a mixture of epoxy resin, fiberglass, metals and non-metals. The content and consistency of the above components in a PCB varies, depending on the type of PCB, type of device, year of manufacture and other factors. Due to the complexity of the PCB, their recycling becomes difficult, by including the pretreatment stage (e.g. dismantling, chipping, etc.). Subsequently, some chemical, mechanical or physical methods can be applied.
In this study, the experimental process followed included collection, disassembly and separation of the main components of waste PCBs, as well as their qualitative and quantitative characterization of the metals they contain. Finally, a hydrometallurgical method was developed aiming at the recovery of specific metals. The acids used for the extraction were hydrochloric, sulfuric and nitric acid. Also, sulfuric acid was used with the addition of hydrogen peroxide. The base metals examined were copper, tin, iron, aluminum and nickel.
With regard to the effects of leaching, a maximum yield was achieved using hydrochloric acid at 30 °C for aluminum, tin and iron, as opposed to nitric acid, which exhibited a maximum extraction yield for copper and nickel.
