Studies on Acidic Leaching of Waste Mobile Phones

Abstract

The consumption of mobile phones is increasing day by day and the replacement speed is also accelerating. Thus, a lot of old mobile phones and their parts need to be processed. Mobile phones contain more than 40 elements and/or materials. This experimental study aims to establish the possibilities of recovering valuable metals from waste mobile phones by using acidic leaching. The process steps include dismantling of waste mobile phones, pre-processing to liberate the materials, and directing them to final treatment processes. Prior to leaching tests, the PCBs of waste mobile phone sample are chemically analyzed and its metal contents are found as 33.22% Cu, 9.42% Fe, 1.86% Zn, 2.77% Ni, 1.63% Al, 0.4% Pb, 0.02% Co, 0.14% Ag, and 251.2 ppm Au. In the leaching experiments, sulfuric, nitric, and hydrochloric acids are used. In the sulfuric acid leaching experiments, effects of acid concentration, temperature, hydrogen peroxide addition, and leaching periods on metal dissolution efficiencies are investigated. Results are compared and discussed in relation to the types of acids. XRD analyses of feed material and leach residues are also carried out. As a result of this experimental study, 97.9% Fe leaching in 8 M H₂SO₄ solutions, 89% Pb, 100% Ni, 90.4% Co, and 4.1% Cu leaching in 1M HNO₃ solutions, 100% Pb, and 100% Al leaching in 4 M HCl solutions in one hour are found. In conclusion, sequential leaching with different acids is recommended for the effective leaching of all metals.