Metal recuperation from obsolete mobile printed circuit boards

With the constant advancement of new cell phone technologies, the exchange of this equipment becomes more frequent, which favors the increase of waste to be disposed of in landfills. In addition to these residues contributing to the depletion of these landfills, they contain metallic materials, plastics and ceramics that can eventually cause an environmental impact on the environment.

To minimize the disposal of waste in landfills and avoid contamination of the environment by potentially toxic substances, some studies on the recovery of materials contained in printed circuit boards (PCI) are being developed by our research group.

The recovery of these materials involves the manual separation of the printed circuit boards from the rest of the device, such as the battery, liquid crystal display and plastic housing, use of mineral treatment techniques and hydrometallurgical processes. The ore treatment techniques that are applied to the treatment of PCI waste involve grinding it in hammer mills and knife mills in order to release the materials contained in the plates; magnetic and electrostatic separation are also applied in order to recover magnetic materials and concentrate non-magnetic materials that generally contain plastics, ceramics and conductive metals that are separated into conductors and non-conductors in the electrostatic separator, another alternative
to concentrate the metals is the granulometric separation.

Characterization tests such as digestion in aqua regia, loss to fire, X-ray fluorescence, inductively coupled plasma mass spectrometry are carried out to assess the effectiveness of mineral treatment processes. Hydrometallurgical processes are adopted in order to selectively separate conductive materials, this process involves the use of acids, oxidizing and reducing solutions to promote the selective removal of metals. With the processing of printed circuit boards using mineral treatment techniques and hydrometallurgical processes, it is possible to recover mainly copper, iron, silver, tin, nickel and lead.