Mendeleev University of Chemical Technology of Russia, Moscow, Russia:

I. A. Pochitalkina, Professor, Doctor of Technical Sciences, e-mail: pochitalkina@list.ru
Kh. F. Le, Postgraduate Student
A. E. Likhosherst, 2^nd Year Master’s Student

Kurnakov Institute of General and Inorganic Chemistry at the Russian Academy of Sciences, Moscow, Russia:

D. F. Kondakov, Senior Researcher, Candidate of Technical Sciences

The Socialist Republic of Vietnam is 21^st in the list of the world’s countries for phosphate ore reserves. The largest apatite ore deposit Lao Cai with the stretch of over 100 km and the total area of 45.56 km² situated along the right bank of the Hong River has been in operation since 1940. According to the prospecting data, the Lao Cai ore reserves exceed 30 mln tons. As the mining operations keep expanding and the environmental regulations grow stricter, it is necessary to monitor the concentration of rare-earth metals in the apatite ore. Inductively coupled plasma mass spectrometry (ICP–MS), a method that enables to directly analyze mineral raw materials and sites for rare-earth elements, cannot be consistently utilized by industrial sector. An alternative spectrophotometric technique, which helps determine the total amount of rare-earth elements in analyzed objects, is time- and labour-consuming. This paper describes the results of a trial that was conducted for an optimized spectrophotometric technique. The advantage of the optimized technique is that it skips the stage when a sample gets decomposed with a mixture of hydrofluoric, nitric and sulphuric acids, which saves time and labour and improves the work safety. The results obtained from both conventional and optimized spectrophotometric techniques have good convergence: the discrepancy between them is 1.68%, which does not exceed the applicable error. The authors performed parallel analysis of two samples of ground Lao Cai apatite ore for rare-earth elements determination. Thus, ICP-MS, as well as conventional and optimized spectrophotometric techniques were applied. The authors determined what caused the errors in the case of the latter and how such errors can be minimized.

1. Volkov A. I., Stulov P. E., Leontiev L. I., Uglov V. A. Analyzing the use of rare earth metals by Russia’s and the world’s ferrous metals industry. Izvestiya vuzov. Chernaya metallurgiya. 2020. Vol. 63, No. 6. pp. 405–418.
2. Dutta T., Kim K.-H., Uchimia M. Global demand for rare earth resources and strategies for green mining. Environmental Research. 2016. Vol. 150. pp. 182–190.
3. Amato A., Becci A., Birloaga A. et al. Sustainability analysis of innovative technologies for the rare earth elements recovery. Renewable and Sustainable Energy Reviews. 2019. Vol. 106. pp. 41–53.
4. Guyonnet D., Planchon M., Rollat A. Material flow analysis applied to rare earth elements in Europe. Journal of Cleaner Production. 2015. Vol. 107. pp. 215–228.
5. Haque N., Hughes A., Lim S. Rare earth elements: Overview of mining, mineralogy, uses, sustainability and environmental impact. Resources. 2014. Vol. 3, Iss. 4. pp. 614–635.
6. Balaram V. Rare earth elements : A review of applications, occurrence, exploration, analysis, recycling, and environmental impact. Geoscience Frontiers. 2019. Vol. 10, Iss. 4. pp. 1285–1303.
7. Papangelakis V. G., Moldoveanu G. Recovery of rare earth elements from clay minerals. Proceedings of the 1^st Rare Earth Resources Conference (Milos). 2014. pp. 191–202.
8. Bashlykova T. V., Valkov A. V., Petrov V. I. The extraction of rare-earth elements from phosphogypsum and waste of gold mines. Tsvetnye Metally. 2012. No. 3. pp. 40–42.
9. Lokshin E. P., Kalinnikov V. T., Tareeva O. A. Extracting rare-earth metals from middlings and wastes of Khibiny apatite concentrate process. Tsvetnye Metally. 2012. No. 3. pp. 75–80.
10. Peiravi M., Dehghani F., Ackah L. et al. A review of rare-earth elements extraction with emphasis on non-conventional sources: Coal and coal byproducts, iron ore tailings, apatite, and phosphate byproducts. Mining, Metallurgy & Exploration. 2021. Vol. 38, No. 1. pp. 1–26.
11. Zhang W., Noble A., Yang X. et al. A comprehensive review of rare earth elements recovery from coal-related materials. Minerals. 2020. Vol. 10, Iss. 5. p. 451.
12. Zhou F., Xiao Y., Guo M. et al. Selective leaching of rare earth elements from ion-adsorption rare earth tailings: A Synergy between CeO2 Reduction and Fe/Mn Stabilization. Environmental Science & Technology. 2021. Vol. 55, Iss. 16. pp. 11328–11337.
13. Shin D., Kim J., Kim B. et al. Use of phosphate solubilizing bacteria to leach rare earth elements from monazite-bearing ore. Minerals. 2015. Vol. 5, Iss. 2. pp. 189–202.
14. Maes S., Zhuang W.-Q., Rabaey K. et al. Сoncomitant leaching and electrochemical extraction of rare earth elements from monazite. Environmental Science & Technology. 2017. Vol. 51, Iss. 3. pp. 1654–1661.
15. Xu Q., Sun Y., Yang L. et al. Leaching mechanism of ion-adsorption rare earth by mono valence cation electrolytes and the corresponding environmental impact. Journal of Cleaner Production. 2019. Vol. 211. pp. 566–573.
16. Fuguo L., Gao G., Li H. et al. Compound leaching of rare earth from the ion-adsorption type rare earth ore with magnesium sulfate and ascorbic acid. Hydrometallurgy. 2018. Vol. 179. pp. 25–35.
17. Kim R., Cho H., Han K. et al. Optimization of acid leaching of rare-earth elements from Mongolian apatite-based ore. Minerals. 2016. Vol. 6, Iss. 3. p. 63.
18. Golev A. Rare earths supply chains: Current status, constraints and opportunities. Resources Policy. 2014. Vol. 41. pp. 52–59.
19. Pochitalkina I. A., Kondakov D. F., Likhosherst A. E. Comparative evaluation of methods for determination of the rare earth elements content in phosphate raw materials. Tsvetnye Metally. 2022. No. 1. pp. 44–48. DOI: 10.17580/tsm.2022.01.05.
20. Mineral commodity summaries. U.S. : Geological Survey, 2022. 202 p.
21. Decision No. 1893 of the prime minister of the Socialist Republic of Vietnam. QD-TTg, Hanoi, 20.10.2014. Approval of the plan for research, operation, processing and utilization of apatite ore reserves till 2020, with an outlook for 2030. Available at: https://vanban.chinhphu.vn/default.aspx?pageid=27160&docid=17700 (Accessed: 12.04.2022).
22. Pochitalkina I. A., Kondakov D. F., Le Kh. F. Control over phosphorus mobility in complex fertilizers obtained from Lao Cai apatite ore. Khimicheskaya tekhnologiya. 2020. Vol. 21, No. 12. pp. 561–564.
23. Lichte F. E., Meier A. L., Crock J. G. Determination of the rareearth elements in geological materials by inductively coupled plasma mass spectrometry. Analytical Chemistry. 1987. Vol. 59, No. 8. pp. 1150–1157.
24. Jarvis K. E. Inductively coupled plasma mass spectrometry: A new technique for the rapid or ultra-trace level determination of the rare-earth elements in geological materials. Chemical Geology. 1988. Vol. 68, Iss. 1-2. pp. 31–39.
25. Jarvis K. E., Williams J. G. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS): a rapid technique for the direct, quantitative determination of major, trace and rare-earth elements in geological samples. Chemical Geology. 1993. Vol. 106, Iss. 3-4. pp. 251–262.
26. Gorbatenko A. A., Revina E. I. Instrumental methods for rare-earth elements determination. Zavodskaya laboratoriya. 2014. Vol. 80, No. 4. pp. 7–19.
27. Astrom M., Corin N. Distribution of rare earth elements in anionic, cationic and particulate fractions in boreal humus-rich streams affected by acid sulphate soils. Water Research. 2003. Vol. 37, No. 2. pp. 273– 280.
28. Zhang X. C., Nearing M. A., Polyakov V. O. et al. Using Rare-Earth Oxide Tracers for Studying Soil Erosion Dynamics. Soil Science Society of America Journal. 2003. Vol. 67, No. 1. pp. 279–288.
29. Savvin S. B. Arsenazo III group organic reagents. Moscow : Atomizdat, 1971. 350 p.
30. Khitrova O. A. Method of photometric determination of rare earth elements. Patent RF, No. 2511375. Applied: 02.07.12. Published: 10.04.14. Bulletin No. 10.
31. Pochitalkina I. A., Kondakov D. F., Le Kh. F., Vu Ch. T. Composition of Lao Cai low-grade apatite ore. Zhurnal neorganicheskoy khimii. 2018. Vol. 63, No. 8. pp. 1046–1049.
32. Mikhailov V. A. The world’s rare-earth ores: Geology, resources, economics. Monograph. Kiev : Izdatelsko-poligraficheskiy tsentr “Kievskiy universitet”, 2010. 223 p.
33. Global market of rare-earth metals and compounds 2019–2025 (9^th edition): Analytical study. Analytical group engaged in studying raw materials markets, metals and their products. International Metallurgical Research Group. 2019. 104 p. Available at: https://docplayer.ru/134894766-Mirovoy-rynok-redkozemelnyhmetallov-i-soedineniy-9-izdanie.html (Accessed: 10.04.2022).