I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials, Kola Science Center of RAS (Russia):

Nikolayev А. I., Deputy Director on Scientific Work, Corresponding Member of RAS, Professor, nikol_ai@chemy.kolasc.net.ru
Melnik N. А., Associate Professor, Ph. D. in Engineering Sciences
Chekanova Yu. V., Engineer
Petrov V. B., Senior Researcher, Ph. D. in Engineering Sciences

REC «Mekhanobr-Tekhnika» (Russia):
Dmitriyev S. V., Chief Specialist, dmitriev_sv@npk-mt.spb.ru

The issues related to decrease of sphene concentrate radioactive nuclides content in beneficiation stage are considered, the main radioactive nuclide being thorium-232. Sphene concentrate from apatite-nepheline ores mined in the Kola Peninsula is distinguished by increased concentration of radioactive nuclides, limiting its application in welding materials and for other purposes. The source of radioactive nuclides in concentrate is perovskite mineral impurity. Decrease in radioactive nuclides content in beneficiation stage was traced by means of mineralogical, radiometric and X-ray phase analyses methods. Dry electromagnetic separation and coronatype electrostatic separation application at increased temperatures permitted to decrease effective radioactivity of concentrate to acceptable level, allowed for application in welding materials. Sphene total losses at the stage of concentrate cleaning from perovskite amounted to 10.6 %. The achieved results require further optimization of electrostatic separation operations regimes. Considering feed material fine size (99 % of size fraction minus 0.2 mm), the results of dry electromagnetic separation and electrostatic separation may be considered wholly satisfactory. This opens a prospect for further improvement of indices in sphene concentrate dry cleaning from radioactive nuclides, as well as commercial implementation of this technology.

1. Pleshakov Yu. V., Alekseev A. I., Brylyakov Yu. Ye., Nikolayev A. I. Obogashchenie Rud, 2004, No. 2, pp. 15–17.
2. Nikolayev A. I., Melnik N. A., Pleshakov Yu. V. Svarochnoe Proizvodstvo, 2000, No. 1, pp. 50–53.
3. Nikolayev A. I., Petrov V. B., Melnik N. A. et al. Tsvetnaya Metallurgia — Non-ferrous Metallurgy, 2005, No. 11, pp. 37–46.
4. Zadorozhnyy V. K., Nikolayev A. I., Melnik N. A. et al. Obogashchenie Rud, 2006, No. 6, pp. 9–12.
5. Ivanov K. S., Kononov O. V., Ustinov I. D. Marksheyderiya i Nedropolzovanie, 2013, No. 4, pp. 46–47.
6. Korovnikov A. N., Ustinov I. D. Zolotodobyvayushchaya Promyshlennost — Gold Mining, 2012, No. 4, pp. 26–27.
7. Vaysberg L. A., Ustinov I. D. Obogashchenie Rud, 2010, No. 5, pp. 25–28.
8. Powder Diffraction File Inorganic Phases Alphabetican Index (Chemical and Mineral Name). International Centre for Diffraction Data, USA, 2010.
9. Metodika izmereniya aktivnosti radionuklidov v schetnykh obraztsakh na stsintillyatsionnom gamma-spektrometre s ispolzovaniyem programmnogo obespecheniya «Progress» (Method for measuring the activity of radionuclides in samples with scintillation counting gamma spectrometer using software «Progress»). Moscow, GP «VNIIFTRI», 1996, 41 p.
10. Vladimirov V. A. Radiatsionnaya i khimicheskaya bezopasnost naseleniya (Radiation and chemical safety of the population). Moscow, Delovoy ekspress, 2005, 543 p.