National University of Science and Technology “MISiS”, Moscow, Russia:

A. S. Kozlov, Post-Graduate Student of a Chair of Certification and Analytical Control, e-mail: kozlovas44@gmail.com
A. D. Tsyrenova, Engineer of a Chair of Non-Ferrous Metals and Gold
E. V. Bogatyreva, Assistant Professor of a Chair of Non-Ferrous Metals and Gold
V. A. Filichkina, Head of a Chair of Certification and Analytical Control

The development results for phosphogypsum and the products of its leaching chemical composition determination method are presented in the work. Main difficulties that appears in the process of rare earth metals determination in phosphogypsum and its leaching products (including their quantity, spectral folding, matrix effects and some specifics of modern Х-ray spectrometers) are considered. This work is introduced with an increased focus on critical values of rare earth elements concentrations in the investigated objects. The measurements were made with ARL Optim’X spectrometer. Work samples certified using optical-emission spectrometry were used. Calibration curves with a high level of linearity for Nd, La, Ce, Pr and Y (recalculated into oxides) were obtained using present certified reference materials. Rare earth element concentrations ranges, calculated values of detections limits, standard errors of estimate and correlation coefficients for calibration curves are presented. Spectral folding and matrix effects are taken into account, thus providing better accuracy of determination. Use of L-series lines intensity as an analytical signal simplifies the choice of analysis parameters due to application of rather low accelerating voltage and widespread types of analyzing crystals (LiF 200). The obtained results show the applicability of Х-ray fluorescence spectrometry for express determination of rare earth elements in phosphogypsum and its leaching products.
This work was carried out within the agreement between the National University of Science and Technology “MISiS” and All-Russian Scientific-Research Institute of Chemical Technology (Moscow, Russia) No. 1/2012 (November 20, 2012), realized with the financial support of the order of the Government of Russian Federation No. 218 (April 09, 2010).

1. GOST 23789–79. Vyazhushchie gipsovye. Metody ispytaniy (State Standard 23789–79. Gypsum binders. Test methods). Introduced: 1980–07–01. Moscow : Publishing House of Standards, 1979. (in Russian)
2. Dvorkin L. I, Dvorkin O. L. Stroymaterialy iz otkhodov promyshlennosti (Construction materials from industrial wastes). Moscow : Feniks, 2007.
3. Saveeva I. L. Redkozemelnaya promyshlennost Rossii: sovremennoe sostoyanie, resursnye usloviya razvitiya (The rare-earth industry of Russia: present status, resource conditions of development). Geografiya i prirodnye resursy = Geography and Natural Resources. 2011. No. 1.
4. Balashov Yu. A. Geokhimiya redkozemelnykh elementov (Geochemistry of rare-earth elements). Moscow : Nauka, 1976.
5. GOST 23862.0–79. Redkozemelnye metally i ikh okisi. Obshchie trebovaniya k metodam analiza (State Standard 23862.0–79. Rare-earth metals and their oxides. General requirements for methods of analysis). Introduced: 1981–01–01. Republished in November 2003 with changes 1,2. Moscow : Publishing House of Standards, 2003. (in Russian)
6. GOST 25702.10–83. Kontsentraty redkometallicheskie. Metod opredeleniya summy redkozemelnykh elementov (RZE) (State Standard 25702.10–83. Raremetallic concentrates. Method for the determination of sum of rare earths). Introduced: 1983–04–05. Republished in May 1994 with changes 1. Moscow : Publishing House of Standards, 1994. (in Russian)
7. Lokshin E. P., Tareeva O. A. Production of high-quality gypsum raw materials from phosphogypsum. Russian Journal of Applied Chemistry. 2015. Vol. 88, No. 4. pp. 567–573.
8. Guitouni M. Optimized and validated wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) method for the determination of uranium in phosphogypsum. Journal of Radioanalytical and Nuclear Chemistry. 2015. Vol. 303, No. 3. pp. 1649–1657.
9. Semenov A. A., Abramov A. M., Sobol Y. B., Galieva Z. N., Galantsev A. V., Gerya V. O. Preparation of Nd2O3 through the extraction separation of rareearth concentrate recovered from phosphogypsum. Inorganic Materials. 2016. Vol. 52, No. 2. pp. 233–237.
10. Kulczycka J., Kowalski Z., Smol M., Wirth H. Evaluation of the recovery of Rare Earth Elements (REE) from phosphogypsum waste — Case study of the WIZÓW Chemical Plant. Journal of Cleaner Production. 2016. Vol. 113. pp. 345–354.
11. Lamzougui G., Nafai H., Bouhaouss A., Bchitou R. Determination of the maximum content of heavy metals in the phosphogypsum. Journal of Materials and Environmental Science. 2016. Vol. 7, No. 6. pp. 2161–2169.
12. Lokshin E. P., Tareeva O. A., Elizarova I. R. Sorption of rare-earth elements from phosphogypsum sulfuric acid leaching solutions. Theoretical Foundations of Chemical Engineering. 2015. Vol. 49, No. 5. pp. 773–778.