India is the third-largest producer of e-waste, generating about 4 million tonnes annually, following China and the US. As the country progresses economically, this volume of waste is only expected to increase. Disposing of waste printed circuit boards (WPCB) poses a challenge due to the complex mix of polymers, metals, and ceramics they contain. However, these boards also hold valuable metals that can be mined.
Various recycling techniques exist, such as electrostatic separation, magnetic separation, and pyrometallurgical and hydrometallurgical methods. Unfortunately, many of these methods focus solely on extracting metals and disregard the polymer and other non-metallic components. This results in the abandonment of low-value parts.
One commonly used method, pyrolysis, involves heating the material in the absence of oxygen. During this process, the metal parts convert to char, while the plastic components turn into gas and liquid. However, pyrolysis is not a one-size-fits-all solution, as different heating parameters yield different outcomes.
In an effort to optimize the pyrolysis of e-waste, researchers from IIT-Guwahati, Bibari Boro and Pankaj Tiwari, utilized a statistical technique known as ‘response surface methodology’. They identified temperature as the most influential parameter and conducted experiments varying the temperature while keeping the heat rate and hold time constant. Through their research, they found that at the optimal temperature, e-waste pyrolysis could yield liquids rich in aromatics with a high calorific value of about 35 MJ per kg, along with hydrogen and methane.
Boro and Tiwari published their findings in the journal Energy, highlighting the comprehensive approach they took to optimize WPCB pyrolysis for enhanced resource recovery. Evidently, with the right conditions, pyrolysis presents a promising solution for effectively managing e-waste and extracting valuable resources from it.
