Challenges for critical raw material recovery from WEEE
the case study of gallium
Ueberschaar, Maximilian; Otto, Sarah Julie; Rotter, Vera Susanne
Gallium and gallium compounds are more frequently used in future oriented technologies such as photovoltaics, light diodes and semiconductor technology. In the long term the supply risk is estimated to be critical. Germany is one of the major primary gallium producer, recycler of gallium from new scrap and GaAs wafer producer. Therefore, new concepts for a resource saving handling of gallium and appropriate recycling strategies have to be designed.This study focus on options for a possible recycling of gallium from waste electric and electronic equipment. To identify first starting points, a substance flow analysis was carried out for gallium applied in integrated circuits on printed circuit boards and LED used for background lighting in Germany in 2012. Moreover, radio amplifier chips (integrated circuits) were investigated in detail to deduct first approaches for a recycling of such components. An analysis of recycling barriers was carried out in order to investigate general opportunities and risks for the recycling of gallium from chips and LED. Results show, that significant gallium losses arose during the production and the waste management. 93 ± 11 %, equivalent to 43,000 ± 4,700 kg of the total gallium potential were lost over the whole process until applied in electronic goods. The largest share of 14,000 ± 2,300 kg gallium was lost in the primary production process. The refining process was connected to additional 6,900 ± 3,700 kg and the chip and wafer production to 21,700 ± 3,200 kg lost gallium. Due to low collection rates, further 400 ± 200 kg of gallium were not recycled. Due to the fact, that no recycling of gallium from WEEE exists, all gallium is lost in the current waste management system. A thermal pre-treatment of the chips, followed by a manual separation allowed an isolation of gallium rich fractions, with mass fractions up to 35 %. Here, gallium loads per Chip were between 0.9 and 1.3 mg. Copper, gold and arsenic were determined as well. The pyrometallurgical copper route might be an option for gallium recycling. A recovery of gold and gallium in combination with copper is possible due to a compatibility with this base-metal. But, a selective separation prior to this process is necessary. Diluted with other materials, the gallium content would be too low and the recovery not feasible any more. The recycling of gallium from chips applied on printed circuit boards and LED used for background lighting is technically complex. Recycling barriers exist over the whole recycling chain. A forthcoming commercial implementation is not expected in nearer future. This applies in particular for gallium bearing chips.
Is Part Of
