2026-04-13T05:57:53Zhttps://recercat.cat/oai/request

oai:recercat.cat:2117/3462292026-02-04T06:54:59Zcom_2072_1033col_2072_452950

00925njm 22002777a 4500 dc Pavón Regaña, Sandra author Fortuny Sanromá, Agustín author Sastre Requena, Ana María author 2021-03-01 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(g) produced from thermal decomposition of NH4Cl(s), 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 gNH4Cl/gsolid 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 gNH4Cl/gsolid, 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. Peer Reviewed Postprint (author's final draft) Àrees temàtiques de la UPC::Enginyeria química Salvage (Waste, etc.) Chlorination Electronic waste Fluorescent powder Rare earths recovery Recycling Cloració Residus -- Recuperació Rare earth elements recovery from secondary wastes by solid-state chlorination and selective organic leaching