STUDY OF METAL RECOVERY FROM PRINTED CIRCUIT BOARDS BY PHYSICAL-MECHANICAL TREATMENT PROCESSES

With the technology advancement of electro-electronic devices, there was an increase in consumption and in the replacement of the equipment in a shorter interval of time. Consequently, the production of waste electrical and electronic equipment (WEEE) has also been increased, becoming not only a sustainability issue but also an environmental problem. In almost all electronic devices it can be found a printed circuit board (PCB), making it an important component of WEEE. It is usually composed of polymers, ceramic material, and metals, in which the metallic fraction of the PCB can vary between 19% and 40% of its weight. It contains heavy metals that can cause environmental impacts due to improper disposal. But on the other hand, there are elements with added value, such as copper, gold, silver, iron, aluminium and critical raw materials, such tantalum that can be recovered, making PCB scrap an economically attractive for recycling. It conserves natural resources, since it prevents new minerals from being extracted and it is a great contribution to the circular economy because, removing the waste from its disposal and reinserts in the production cycle. Thus, the main objective of this work is to characterize the PCB and study the physical-mechanical processing (through grinding, granulometric, magnetic, electrostatic and gravity separations) in order to concentrate metals, especially copper, identifying the main elements obtained through the processes applied. For this, initially, studies were carried out on the characteristic composition of printed circuit boards through the electron microscope. Then, the PCB was processed in a cutting mill in order to release the materials, and after the granulometric separation was performed. For each size classification resulted, a magnetic separation was performed. Subsequently, on the non-magnetic fraction, electrostatic separation was performed, in which the material was separated into conductive, mix and non-conductive fraction, and also it was performed a gravity separation, in which the material was separated into concentrated, middling and tailing. After all the separation processes, the different products obtained were observed with the microscope to qualitatively assess the metallic content. In the recovery of metals by electrostatic separation, the efficiencies obtained were 61% for the upper particle size (+1.18mm) and 91% for the lower particle size (-0.3mm). In gravity separation, the metal recovery was 66% for the particle size -0.6 + 0.3 mm and 80% for the particle size -1.18 + 0.6mm. Thus, by the end of this work, it is possible to conclude that physical-mechanical techniques have high potential for the production of a concentrate with high added value.