Massive Recycling of Waste Mobile Phones: Pyrolysis, Physical Treatment, and Pyrometallurgical Processing of Insoluble Residue

Waste mobile phones (WMP) consisting of a heterogeneous mixture of metal, plastic, glass, and ceramic materials have either disposal or recycling problems. Pyrolysis can prevent the release of dioxin because organic materials are decomposed during the heating process. This paper reports a three-step massive treatment of WMP by pyrolysis, physical treatment, and pyrometallurgical processing. The release of dioxin was significantly limited during pyrolysis. Miscellaneous solid parts after pyrolysis (= 488 kg/ton-WMP) were physically separated into char (= 181 kg/t-WMP), iron scrap (= 7S kg/t-WMP), printed circuit boards (PCBs = 121 kg/t-WMP), and insoluble residue (= 111 kg/t-WMP). Here, the smelting of insoluble residue was carefully investigated to simulate the recovery of precious metals (gold and silver) and critical metals (nickel and tin) in a molten state. The recovery rate of valuable elements was influenced by the terminal velocity of metallic particles in the liquid slag in association with slag viscosity and silicate structures. The comprehensive metal recovery system can produce substantial amounts of copper (82.7 kg), gold (0.1 kg), silver (0.3 kg), nickel (1.5 kg), and tin (3.3 kg) from the processing of 1000 kg of WMP.