Navoi State University of Mines and Technologies (Navoi, Uzbekistan)
Khurramov N. I., Associate Professor, PhD in Engineering Sciences, nava2121@mail.ru
Nurmurodov T. I., Professor, Doctor of Engineering Sciences, t.nurmurodov@gmail.com

Tashkent Institute of Chemical Technology (Tashkent, Uzbekistan)
Erkaev A. U., Professor, Doctor of Engineering Sciences

This article presents the results of a study of phosphate rocks from the Aznek deposit (Central Kyzylkum, Uzbekistan) aimed to establish the content of rare earth elements (REE) in their composition in order to identify whether the REE may be recovered to yield standard products for further processing. REE are not typically recovered separately in the manufacture of phosphate fertilizers. The presence and contents of these elements, however, affect the commercial properties of mineral fertilizers. Moreover, phosphate rocks are extensively processed for large-scale production of phosphate fertilizers. Closer attention is therefore paid to the associated recovery of REE, with their mass fraction amounting to 0.8–0.9 %, and sometimes reaching up to 5 %. Chemical, neutron activation, and spectrometric analyses were conducted in order to establish the REE content in the phosphate rocks of the Aznek deposit and select a suitable recovery method. The analysis results provide data on the content of 16 REEs. The highest values were found for Nd (neodymium), La (lanthanum), and Ce (cerium) that are available in the phosphate rocks of the Aznek deposit in the amounts of 30, 48 and 65 g/t, respectively. Among the proposed phosphate rock processing methods, the most effective method for REE recovery is decomposition with nitric acid, which renders both valuable REE concentrates and phosphorus and nitrogen fertilizers. Phosphate rock decomposition experiments have been carried out using 55 % nitric acid. In order to improve REE recovery, NaNO₃ or Na₂CO₃ was introduced into the solution as it enables precipitation of fluorine ions (60–70 %). A preliminary process has been proposed for the phosphate rocks of the Aznek deposit, which may also be utilized for rare earth element recovery.

1. Makhov S. V., Olifson A. L. Technology of extraction of rare earth elements from extraction phosphoric acid obtained during processing of apatite concentrate. Мoscow, 2019. 284 p.
2. Oljaev D. N., Nurmurodov T. I., Khurramov N. I., Sharipov S. Sh. Effect of mechanochemical treatment of lowgrade phosphorites on the optimal composition of phosphorus fertilizers. Obogashchenie Rud. 2023. No. 3. pp. 16–22.
3. Sanakulov K. S., Mukhiddinov B. F., Sharipov S. Sh., Vapoev Kh. M. Analyzing how ions tend to form in the aqueous phase of the slurry and how they affect the bacterial oxidation of sulphide minerals. Tsvetnye Metally. 2022. No. 5. pp. 15–23.
4. Kodirov S., Mukhiddinov B., Ikramov А., Vapoyev Kh., Umrzokov А., Sharipov S. Synthesis of methylpyridines by catalytic method in the gas phase. E3S Web of Conferences. 2023. Vol. 417. DOI: 10.1051/e3sconf/202341702010

5. Umirov F. E., Shodikulov Zh. M., Aslonov A. B., Sharipov S. Sh. Material composition of talc-magnesite rocks of the Zinelbulak deposit in Uzbekistan. Obogashchenie Rud. 2023. No. 4. pp. 25–31.
6. Kashulin N. A., Denisov D. B., Sandimirov S. S., Dauvalter V. A., Kashulina T. G., Malinovsky D. N., Vandysh O. I., Ilyashuk B. P., Kudryavtseva L. P. Anthropogenic changes in water systems of the Khibiny mountain range (Murmansk region). In 2 vol. Vol. 1. Apatity: Publishing House of the KSC RAS, 2008. 250 p.
7. Litvinova T. E. Obtaining compounds of individual REM and additional products in the processing of low-quality rare metal raw materials: diss. for the degree of Doctor of Engineering Sciences. St. Petersburg, 2014. 318 p.
8. Avramchik A. N., Andrienko O. S., Anufrieva S. I. et al. Modern technologies of the rare metal and rare earth industry. Tomsk: NTL Publishing House, 2016. 388 p.
9. Moldoveanu G. A., Papangelakis V. G. Recovery of rare earth elements adsorbed on clay minerals: I. Desorption mechanism. Hydrometallurgy. 2012. Vol. 117–118. pp. 71-78.
10. Vinnik M. M., Erbanova L. N., Zaitsev P. M. et al. Methods for the analysis of phosphate raw materials, phosphorus and complex fertilizers, feed phosphates. Мoscow: Khimiya, 1975. 218 p.
11. Zaitsev E. I., Reznikov R. S., Sotskov Yu. P. Neutron activation analysis of rocks for rare elements. Moscow: Nedra, 1978. 101 p.
12. Muzafarov А. М., Kulmatov R. А. Neutron-activation method for analysis of determination of chemical elements in underground and industrial waste water. Universum: Technical Sciences: Electronic Scientific Journal. 2020. No. 12. URL: https://7universum.com/ru/tech/archive/item/11113 (accessed: 14.03.2024).
13. Van'kova N. R., Tulina O. V. Study of the metrological characteristics of the mass spectrometric method for measuring mass concentrations of chemical elements. Tekhnika. Tekhnologii. Inzheneriya. 2019. No. 3. pp. 28–33.
14. Corbett M. K., Eksteen J. J., Niu X. Z., Croue J. P., Watkin E. L. J. Interactions of phosphate solubilising microorganisms with natural rare-earth phosphate minerals: a study utilizing Western Australian monazite. Bioprocess and Biosystems Engineering. 2017. Vol. 40, Iss. 6. pp. 929–942.
15. Umirov F. E., Shodikulov Zh. M. Scientific and technological principles of the complex use of serpentinite of the Karmaninskoe deposit. Obogashchenie Rud. 2022. No. 1. pp. 41–46.
16. Temirov U., Doniyarov N., Jurakulov B., Usanbaev N., Tagayev I., Mamataliyev A. Obtaining complex fertilizers based on low-grade phosphorites. E3S Web of Conferences. 2021. Vol. 264. DOI: 10.1051/e3sconf/202126404009
17. Cheremisina O. V., Sergeev V. V., Fedorov A. T., Mikheeva V. Yu. Intensification of leaching of rare earth metals from phosphogypsum. Obogashchenie Rud. 2021. No. 5. pp. 46–52.
18. Akhtamova M., Temirov U., Khurramov N., Shukurov A., Karshiev B. Processing of phosphorites and additives with researching their thermodynamical properties. E3S Web of Conferences. 2023. Vol. 434. DOI: 10.1051/e3sconf/202343403016
19. Cheremisina O. V., Sergeev V. V., Fedorov A. T., Alferova D. A. Separation of rare-earth metals and titanium in complex apatite concentrate processing. Obogashchenie Rud. 2020. No. 5. pp. 30–34.