Institute of Chemical Technology, TU Bergakademie Freiberg, Leipziger Straße 29, 09599 Freiberg, Germany; Chemical Engineering Department, EPSEVG, Universitat Politècnica de Catalunya, Víctor Balaguer 1, 08800 Vilanova i la Geltrú, Spain.
Institute of Chemical Technology, TU Bergakademie Freiberg, Leipziger Straße 29, 09599 Freiberg, Germany; Institute of Low-Carbon Industrial Processes, DLR German Aerospace Center, Walther-Pauer-Straße 5, 03046 Cottbus, Germany.
Waste Manag. 2021 Mar 1;122:55-63. doi: 10.1016/j.wasman.2020.12.039. Epub 2021 Jan 22.
Processing of end-of-life products (EoL) containing rare earth elements (REE) has gained increasing importance in recent years with the aim of avoiding supply risks. In addition, circular economy renders complete recirculation of technology metals mandatory. Fluorescent lamp wastes are an important source for REE recovery since they contain significant amounts, up to 55 wt%, of Y and Eu in red phosphors. For these purposes, solid-state chlorination (SSC) is an economically attractive alternative to wet acid leaching treatment, which profits from a considerable reduction of chemicals consumption and process costs. Chlorination takes place with dry HCl produced from thermal decomposition of NHCl, not only converting the REE content of the Hg-free phosphor waste into water soluble REE metal chlorides, but also avoiding the implications of aqueous complex chemistry of REE. To establish an industrial process viable on a commercial scale, the SSC process has been optimized by (i) using a design of experiment (DOE) varying temperature, residence time, and g/g ratio and (ii) improved leaching of the chlorinated metals with an organic mixture selective for REE. As a result, 95.7% of the Y and 92.2% of the Eu were selectively recovered at 295.9 °C, 67 min and a ratio of 1.27 g/g, followed by quantitative selective leaching of the REE. Owed to its low chemicals consumption and operation costs, the current process allows for valorizing lamp waste even when raw material prices are low.
近年来，随着避免供应风险的目标的出现，处理含有稀土元素（REE）的报废产品（EoL）变得越来越重要。此外，循环经济要求技术金属完全再循环。荧光灯废物是 REE 回收的一个重要来源，因为它们含有大量的 Y 和 Eu，高达 55wt%，在红色荧光粉中。出于这些目的，固态氯化（SSC）是湿法酸浸处理的一种经济上有吸引力的替代方法，它得益于化学药品消耗和工艺成本的显著降低。氯化是用热分解 NHCl 产生的干 HCl 进行的，不仅将无汞荧光粉废物中的 REE 含量转化为水溶性 REE 金属氯化物，而且避免了 REE 水相复杂化学的影响。为了在商业规模上建立可行的工业工艺，通过（i）使用实验设计（DoE）改变温度、停留时间和 g/g 比，以及（ii）使用对 REE 具有选择性的有机混合物改进氯化金属的浸出，优化了 SSC 工艺。结果，在 295.9°C、67 分钟和 1.27 g/g 的比例下，选择性地回收了 95.7%的 Y 和 92.2%的 Eu，随后对 REE 进行了定量选择性浸出。由于其化学药品消耗和运营成本低，即使原材料价格低廉，当前的工艺也允许对灯废物进行增值利用。
