Ueberschaar Maximilian, Otto Sarah Julie, Rotter Vera Susanne
Technische Universität Berlin, Institute of Environmental Technology, Sekr. Z2, Chair of Circular Economy and Recycling Technology, Straβe des 17. Juni 135, D-10623 Berlin, Germany. Electronic address: http://www.circulareconomy.tu-berlin.de.
Technische Universität Berlin, Institute of Environmental Technology, Sekr. Z2, Chair of Circular Economy and Recycling Technology, Straβe des 17. Juni 135, D-10623 Berlin, Germany.
Waste Manag. 2017 Feb;60:534-545. doi: 10.1016/j.wasman.2016.12.035. Epub 2017 Jan 12.
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 applied on printed circuit boards and for LEDs used for background lighting in Germany in 2012. Moreover, integrated circuits (radio amplifier chips) were investigated in detail to deduce 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 LEDs. Results show, that significant gallium losses arose in primary production and in waste management. 93±11%, equivalent to 43,000±4700kg of the total gallium potential was lost over the whole primary production process until applied in electronic goods. The largest share of 14,000±2300kggallium was lost in the production process of primary raw materials. The subsequent refining process was related to additional 6900±3700kg and the chip and wafer production to 21,700±3200kg lost gallium. Results for the waste management revealed only low collection rates for related end-of-life devices. Not collected devices held 300 ± 200 kg gallium. Due to the fact, that current waste management processes do not recover gallium, further 80 ± 10 kg gallium were lost. A thermal pre-treatment of the chips, followed by a manual separation allowed an isolation of gallium rich fractions, with gallium mass fractions up to 35%. Here, gallium loads per chip were between 0.9 and 1.3mg. Copper, gold and arsenic were determined as well. Further treatment options for this gallium rich fraction were assessed. The conventional pyrometallurgical copper route might be feasible. 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. The recycling of gallium from chips applied on printed circuit boards and LEDs 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 chips carrying gallium.
镓及其化合物在光伏、发光二极管和半导体技术等面向未来的技术中应用更为频繁。从长期来看，供应风险估计至关重要。德国是主要的原生镓生产国、新废料中镓的回收国以及砷化镓晶圆生产国之一。因此，必须设计出节约资源处理镓的新概念和适当的回收策略。本研究聚焦于从废弃电子电气设备中回收镓的可能方案。为确定初步切入点，对2012年德国印刷电路板上应用的集成电路以及用于背景照明的发光二极管中所使用的镓进行了物质流分析。此外，还对集成电路（射频放大器芯片）进行了详细研究，以推断此类组件回收利用的初步方法。开展了回收障碍分析，以研究从芯片和发光二极管中回收镓的总体机遇和风险。结果表明，在原生生产和废物管理过程中出现了大量镓损失。在整个原生生产过程直至应用于电子产品之前，93±11%，相当于43000±4700千克的总镓潜力损失掉了。在原生原材料生产过程中损失的镓份额最大，为14000±2300千克。随后的精炼过程又额外损失了6900±3700千克，芯片和晶圆生产过程损失了21700±3200千克镓。废物管理结果显示，相关报废设备的回收率很低。未回收的设备含有300±200千克镓。由于目前的废物管理流程无法回收镓，又额外损失了80±10千克镓。对芯片进行热预处理，随后进行人工分离，可以分离出富镓馏分，镓质量分数高达35%。此处，每个芯片的镓负载量在0.9至1.3毫克之间。还测定了铜、金和砷。评估了对此富镓馏分的进一步处理方案。传统的火法冶金炼铜路线可能可行。由于与这种贱金属具有兼容性，有可能将金和镓与铜一起回收。但是，在此过程之前需要进行选择性分离。与其他材料混合后，镓含量会过低。从印刷电路板上的芯片和用于背景照明的发光二极管中回收镓在技术上很复杂。在整个回收链中都存在回收障碍。预计在不久的将来不会有商业应用。对于含镓芯片尤其如此。
