Pyrolysis of Printed Circuit Boards

Printed Circuit Board (PCB) is an essential component of almost all electrical and electronic equipments. The rapid growth of the use of such equipments has contributed enormously to the generation of large quantity of waste PCBs. The WPCBs not only contain valuable metals but also a large variety of hazardous materials. Conventional treatments of such WPCBs have their own limitations. By pyrolysis of WPCBs, it is not only possible to obtain the organic part of it as a fuel or useful chemical but can make further processing to recover metals much easier and efficient. In the present work, a kinetic study on the low temperature pyrolysis of WPCBs using a thermogravimetric analyser has been attempted. The TG analysis was conducted in nitrogen and air atmospheres in the temperature range of 200-600℃ at a heating rate of 40℃/min. The kinetic expressions for both the environments were determined and the activation energies were found to be 110.7 and 90.2 kJ/mol for nitrogen and air, respectively. The effect of thermal pre-treatment on the subsequent copper leaching in nitric acid for untreated, pyrolysed and air-burned PCB was also studied. Copper recoveries from these samples were 30.4%, 92.5% and 96.2%, respectively indicating the importance of thermal pre-treatment in leaching of the metal content.