Development of a Physical Separation Route for the Concentration of Base Metals from Old Wasted Printed Circuit Boards

Abstract

Wastes from old electronic devices represent a significant part of the electronic scrap generated in developing countries, being commonly sold by collectors as low-value material to recycling hubs abroad. Upgrading the quality of this waste type could drive the revenue of recyclers, and thus, boost the recycling market. On this basis, this study investigated the possibility of concentrating metals from old wasted printed circuit boards through a physical separation-based route. Preparation of samples comprised fragmentation, size classification, density, and magnetic separation steps, followed by chemical and macro composition analysis. Cu, Al, Fe, and Sn constituted the major metals encountered in the scraps, including some peak concentrations of Zn, Sb, Pb, Ba, and Mn. Four distinct concentrate products could be obtained after suitable processing: (a) a light fraction composed of plastics and resins; (b) an aluminum concentrate; (c) a magnetic material concentrate, containing mainly iron; (d) a final concentrate containing more than 50% in mass of copper and enriched with nonferrous metals. Preliminary evidence showed that further processes, like the separation of copper wires through drumming, can potentially improve the effectiveness of the proposed processing circuit and should guide future works.

Gravity Concentration in Urban Mining Applications—A Review

“…On this basis, Buzin et al [93] proposed a separation process employing three-stage dense-media separation (using heavy organic liquids) of three different crushed PCB size ranges (+5 mm, −5 + 2 mm, and −2 mm) to obtain a non-metallic concentrate (−2.1 g/cm 3 ), an aluminum concentrate (−2.8 + 2.1 g/cm 3 ), and a dense metals concentrate (+2.8 g/cm 3 ). Subsequently, the latter was subjected to magnetic separation to yield a ferromagnetic concentrate and a copper-rich product with enrichment ratios (concentrate grade/feed grade) greater than six.…”

“…Plastic-film-laminated paper packaging (e.g., Tetra Pak), electric cables, printed circuit boards (PCBs), and pharmaceutical blisters are just a few examples of wastes that necessitate distinct dismantling and liberation methods. While PCBs may be effectively liberated through conventional crushing [93,94], pharmaceutical blisters might require electro fragmentation [95], whereas chemical treatment like dissolution delamination may be an option for plastic-film-laminated paper [96].…”

“…It is worth noting that some specific characteristics of liberated PCBs can present challenges for dense media separation: (a) porous and fibrous materials may absorb the liquid medium, modifying their apparent density; (b) aluminum from oil-filled electrolytic capacitors may exhibit hydrophobic properties, promoting the attachment of air bubbles and further changing their apparent density; (c) copper wires are frequently intertwined with non-metallic materials, potentially causing short circuits [93].…”

Nickel Silicide Catalyst from Photovoltaic Waste for the Methanation Reaction

“…Breakthrough innovations in existing technologies, and the development of a wide range of new ones, simplify our lives [1]; however, they also stimulate an increase in the consumption of raw materials for both semiconductor and rare earth elements [2]. Nevertheless, this is associated with a strong environmental impact, such as the loss of raw material deposits, pollution caused by the technological processing and refining of raw materials, high energy consumption [3] and, most importantly, increased amounts of electronic waste [4]. In 2016, only 20% of the world's electronic waste was properly recycled, and the fate of the remaining 80% is not documented.…”