This study presents a hydrometallurgical process for the leaching and recovery of tin from waste-printed circuit boards (wPCBs). The process aims to separate and recover tin from filter dust produced during the crushing of wPCBs in a recycling facility. The separation of the metallic and non-metallic fractions was carried out by gravimetric separation. The metallic fraction consisted mainly of Cu (23.8%), Fe (17.8%), Sn (12.7%), Pb (6.3%), and Zn (3.4%). During the leaching tests, the effects of (a) HCl concentration (2, 4, 6 M), (b) pulp density (0.1, 0.2, 0.3 g/mL), and (c) the addition of NaCl (no addition, 1 M, 3 M) were investigated. All tests were conducted at an ambient temperature without agitation. A leaching efficiency of 78.2% was obtained during leaching with 6 M HCl and 0.3 g/mL pulp density, while 94.8% of tin was leached under the same conditions with the addition of 3 M NaCl. Tin was recovered from the pregnant solution by addition of 2 M NaOH at pH = 3.0, with an efficiency of 97.4%. The precipitate, despite being amorphous, was easily filtered and it consisted of 64.7% Sn and less than 2% of impurities. The proposed process consists of a leaching stage with 6 M HCl, 3 M NaCl, 0.3 g/mL pulp density, and a contact time of 24 h, and a recovery stage by chemical precipitation at pH = 3.0. The total tin recovery of the suggested process was 92.3%.

The current study presents an effort to develop a sustainable hydrometallurgical process for the recovery of copper from waste printed circuit boards (PCBs) to be applied at local small to medium industrial units. The process aims to separate and recover copper from filter dust produced during the crushing of PCBs using a hammer mill in a recycling facility. Due to the high plastic content in the dust (approximately 30% w/w), the metal fraction was separated gravimetrically, and the material originated consisted mainly of Cu (23.8%), Fe (17.8%), Sn (12.7%), Pb (6.3%), Zn (3.4%), Al (3.3%), Mn (1.6%), and Ni (1.5%). Prior to copper recovery, the dust was leached with HCl as a pretreatment step. During this step, more than 80% of iron, zinc, and tin were leached out. The resulting solid consisted mainly of Cu (37.6%) and Fe (10.7%), leading to a copper enrichment of around 60% in the powder. The leaching of copper was conducted in a two-step process using H₂SO₄ as a leaching agent with the addition of H₂O₂ as an oxidizing agent. The experimental conditions had low energy requirements (no heating or agitation needed). The leaching of Cu reached 98%. Despite the pretreatment step, the concentration of other metals (Fe, Zn, Ni) in the pregnant solution was too high to proceed to electrowining. Therefore, the organic solvent ACORGA M5640 was selected for the extraction of copper from the pregnant solution. The extraction was conducted in two stages at pH equilibrium 1.5, and the loaded organic phase was stripped with HCl in two steps. The strip liquor was suitable for electrowinning.