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Selective Reduction and Separation of Europium from Mixed Rare-Earth Oxides Recovered from Waste Fluorescent Lamp Phosphors

  • Mark L. StraussEmail author
  • Brajendra Mishra
  • Gerard P. Martins
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

Nearly the entire worldwide production of europium is recovered, as a minor constituent, from mining bastnäsite, monazite ore, or ion absorbing clays. However, this research indicates a process to recycle europium from waste lamp phosphors as a strategy meet the demand for europium. In this process, waste fluorescent lamp powder is retorted, sieved, leached, and precipitated to produce a mixed europium/yttrium rare earth oxide (REO). Europium is separated from yttrium by selectively reducing Eu(III) to Eu(II) using zinc powder and precipitating europium (II) sulfate from solution using sulfuric acid. Screening experiments were conducted observe the effect of pulp density, precipitation time, entrance pH, and stoichiometric ratio sulfate upon the grade and recovery of europium (II) sulfate. The best conditions to maximize grade and recovery of europium (II) sulfate were a 1 h precipitation time, 10× the stoichiometric ratio of sulfate, 100 g/L mixed REO, and the entrance pH equal to 3. The maximum grade of europium sulfate was 95.93%, and the maximum recovery was 73.32%.

Keywords

Waste fluorescent lamp Phosphor dust Rare earths Recycling Europium 

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Copyright information

© The Minerals, Metals & Materials Society 2018

Authors and Affiliations

  • Mark L. Strauss
    • 1
    Email author
  • Brajendra Mishra
    • 1
  • Gerard P. Martins
    • 2
  1. 1.Worcester Polytechnic InstituteWorcesterUSA
  2. 2.Colorado School of Mines(Kroll Institute of Extractive Metallurgy)GoldenUSA

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