Material flow analysis and energy requirements of mobile phone material recovery processes

Abstract

Proper recycling of mobile phones and other electronic products is important in order to reduce the generation of large amounts of hazardous waste, lessen environmental and social problems associated to the extraction of minerals and primary production of materials, and also minimize the depletion of scarce materials that are often difficult to substitute. Current material recovery processes are used to recycle electronic waste of various compositions. Based on a review of the recycling processes and material flow analysis (MFA), we attribute the material and energy required to recover metals from 1 tonne of discarded mobile phones. We estimate that the recovery rates of gold, palladium, silver, copper, nickel, lead, antimony, and tin from the recycling processes described are 80 to 99 % (16.4 % of the phone in weight). The two main industrial processes used at present time (pyrometallurgical and combined pyro-hydrometallurgical) have similar energy consumptions (7,763 and 7,568 MJ/tonne of mobile phones, respectively). An average tonne of used mobile phones represents a potential of 128 kg of copper, 0.347 kg of gold, 0.15 kg of palladium, 3.63 kg of silver, 15 kg of nickel, 6 kg of lead, 1 kg of antimony, and 10 kg of tin as well as other metals that are not yet profitable to recover but might be in the future. We find that the energy consumed to recover copper from mobile phones is half of that needed for copper primary extraction and similar or greater energy savings for precious metal refining. Nevertheless, only 2.5 % of mobile phones arrive to industrial recovery facilities. There is a great potential to increase the amount of metals being recovered, thereby reducing energy consumption and increasing resource efficiency.