JSC “Giredmet”, Moscow, Russia:

S. A. Vasilenko, Leading Production Engineer
O. V. Yurasova, Head of Laboratory of High-Purity Substances Production Technology, e-mail: OVYurasova@giredmet.ru
T. V. Dobrynina, Production Engineer
A. B. Arzmanova, Researcher

We considered the production of individual rare earth metal oxides (europium and yttrium) from luminophore wastes using raw material chlorination methods at the stage of its opening and extraction with carboxylic acid at the stage of yttrium and europium separation. Additional purification of the lanthanide compounds from non rare earth impurities was accomplished by the precipitation of their oxalates. Extraction of yttrium and europium from chloride solutions was studied using Versatic 911, caprylic and oleic acids. All extractants were preliminarily treated with a 25% of ammonia water to produce an ammonia soap, which was subsequently used for extraction of lanthanides. For each extractant, the distribution of metals was studied by adjusting the pH of the aqueous phase. The coefficients of separation of the Eu/Y pair by carboxylic acids were determined. The maximum value for Versatic 911, caprylic acid and oleic acid is 2.04, 4.94 and 5, respectively, which is sufficient to separate the pair in the extraction cascade. The disadvantages of Versatic 911 are the smallest separation coefficients. Caprylic acid is characterized by a tendency to form precipitation during extraction. Therefore, further studies were performed on oleic acid, with additional advantages being affordability, low cost and domestic production. Studies on the extraction of yttrium and europium were carried out on model solutions and confirmed by results on technological solutions containing 125 g/l of the sum of lanthanides (96% yttrium and 4% europium) and up to 10 g/l zinc. The calculation of the counter-current cascade was executed and modeled for production of individual oxides of these rare earth metals. The purity of the oxides obtained by the processing of luminophore waste was 99.91% of europium and 99.90% of yttrium.
This work was carried out with the financial support of the Ministry of Education and Science of Russia within the Agreement 14.579.21.0138 (03.10.2016), unique identifier RFMEFI57916X0138.

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