RECOVERY OF METALS FROM DISCARDED MOBILE PHONES

Abstract

The huge amount of toxic waste creation is observed in recent years due to an excessive increment in consumption and rapid transformation in generation of mobile phones. The limited natural resources, rigorous environmental problems, and increasing demand are key factors for recycling of mobile phones. Li-ion batteries and printed circuit boards are essential constituent present in any type of mobile phones and are a valuable secondary raw material for recovery of critical and precious metal values. In this study, an eco-friendly, simple, and robust process was proposed for recovery of lithium, cobalt and manganese values from Li-ion battery and copper concentrate from printed circuit board. The spent Li-ion batteries were discharged, manually dismantled and separated into cathode and anode sheets. Both cathode and anode sheets were cut into pieces and crushed in an attritor mill followed by sieving to obtain cathode and anode active material. Graphite was mainly found in anode material, while LiCoO2 and LiMn2O4 were observed in cathode material. Heat treatment process was carried out to reduce cathode material using graphite (Anode material) in microwave. The heat-treated reduced mass obtain after reduction was dissolved in water with S/L: 1/50. Leach residue was magnetically separated while leach solution was dried. The obtained magnetic fraction contains cobalt and manganese oxide whereas graphite was found in nonmagnetic and leach solutions was mainly found as lithium carbonate solution. Whereas, in order to recover copper from the waste printed circuit board of mobile phones, cut into small pieces and grounded to -0.5mm size consist of 30-40% metal values and 60-70% plastic and organic fraction. Due to the presence of a high amount of plastic resin in feed, separation of plastic and the organic fraction is necessary for the effective recycle of the printed circuit board. A physical step is necessary to provide an aid in increasing economy of metal recovery process from printed circuit board as well as reduce the environmental effect like generation of toxic gases like dioxin and furans while treated at high temperature. An economically and environment friendly fluidization setup were used for increasing concentration of metallic fraction by separation of plastic from the feed. Water fluidization is carried out to upgrade the metal concentration up to ~80-90%. An eco-friendly, simple, and robust process was proposed which can be promising step to recover various precious and critical metals like cobalt, lithium, manganese and copper with a remarkable purity and yield from mobile phones.