Tananaev Institute of Chemistry and Technology of Rare Elements and Minerals, Kola Science Center, Russian Academy of Sciences, Apatity, Russia:

L. G. Gerasimova, Chief Researcher, Doctor of Engineering Sciences, l.gerasimova@ksc.ru
A. I. Nikolaev, Head of Laboratory, Corresponding Member of the Russian Academy of Sciences, Doctor of Engineering Sciences
E. S. Shchukina, Researcher, Candidate of Engineering Sciences
I. V. Safonova, Candidate of Engineering Sciences

The modern scheme of apatite–nepheline ore beneficiation is aimed at the extraction of apatite and partially nepheline. The remaining minerals are practically lost due to the lack of demand and, therefore, are stored in vast tailings dumps which worsen the ecological situation. Among the unused minerals, the practical interest is drawn by calcium titanosilicate— sphene which includes titanium. Given the current scale of ore mining, up to 200 thousand tons of TiO₂ of this deficient element are lost annually. An original method has been developed for separation of the titanium-bearing minerals from waste in the form of the sphene concentrate. The method is based on treatment of the mineral with dilute hydrochloric acid (50 g×l^-1 HCl). This allows separation of acid-soluble mineral components—apatite, nepheline, titanomagnetite, and production of sphene concentrate (CaSiTiO₅) with the titanium dioxide content of 29–31.5%. Calcium is leached from sphene by thermal decomposition with concentrated hydrochloric acid. In this case, titanium and silicon are deposited in the form of the two-phase precipitate—SiO₂ (silica)×TiO₂ (rutile)×xH₂O, which is the parent subject for the synthesis of the functional materials. The efficiency of the highenergy shock–shear action on sphene particles and the titanosilicate parent subjects, which violates their structure and morphology, has been determined. The thermodynamic stability of the activated particles is achieved by chemisorption or firing to obtain the modified products. Due to the high degree loosening of the surface layer of sphene particles under mechanical activation, the ability of the materials to adsorb modifying substances increases. In preparation of mineral pigment, it is recommended to treat activated sphene particles with phosphoric acid. Hardly soluble calcium and titanium phosphates formed in this process improve the whiteness of the pigment product and its resistance to the moisture and temperature changes. The method for the production of hybrid fillers for special adhesives and sealants has been developed. In general, this article illustrates expediency of the use of the manmade waste in dressing of apatite–nepheline ores, in particular the froth product of nepheline flotation, to obtain deficient import-substituting titanium-containing products necessary for the development of the advanced industries, as well as to solve the acute environmental problems in mining, nonferrous metallurgy and defense facilities.

1. Konopleva N. G., Kalashnikov A. O., Ivanyuk G. Yu. Possibility of calculation of trace elements concentrations in minerals of the Khibiny apatite–nepheline ores according to ordinary sampling. Trudy Fersmanovskoy nauchnoy sessii GI KNTs RAN. 2019. No. 16. pp. 283–287.
2. Fedorov S. G., Nikolaev A. I., Brylyakov Yu. E., Gerasimova L. G., Vasileva N. Ya. Chemical processing of mineral concentrates of Kola Peninsula. Apatity : Izdatelstvo KNTs RAN, 2003. 196 p.
3. Ivanyuk G. Yu., Konopleva N. G., Pakhomovskiy Ya. A., Yakovenchuk V. N., Mikhailova Yu. A., Bazay A. V. Titanite of the Khibiny alkaline massif (Kola peninsula): new data. Geology of Ore Deposits. 2016. Vol. 145, No. 3. pp. 36–55.
4. Motov D. L. Physicochemistry and sulfate technology for titanium–rare metal minerals. Apatity : KNTs RAN, 2002. Vol. 2. 163 p.
5. Chaptman D. M., Roe A. L. Synthesis, characterization and crystal chemistry of microporous titanium-silicate materials. Zeolites. 1990. Vo l. 10, Iss. 8. pp. 730–737.
6. Motov D. L., Maksimova G. K. Sphene and its chemical conversion into titanium pigments and fillers. Leningrad : Nauka, 1983. 88 p.
7. Goryachev A. A., Dvegubskiy N. S. Sulfuric acid treatment of sphene concentrate. Lakokrasochnye materialy i ikh primenenie. 1990. No. 4. pp. 30–34.
8. Shchukina E. S., Gerasimova L. G., Maslova M. V. Synthesis of the complex titanium (IV) salt – effective tanning agent for leather and fur. Fundamentalnye issledovaniya. 2018. No. 11-1. pp. 18–23.
9. Latyshev Yu. V., Lenev A. M., Semenov N. F. Anticorrosion pigments. Lakokrasochnye materialy i ikh primenenie. 1997. No. 2. pp. 14–18.
10. Golewski G. L. Estimation of the optimum content of fly ash in concrete composite based on the analysis of fracture toughness tests using various measurings ystems. Construction and Building Materials. 2019. Vol. 213. pp. 142–155.
11. Zhaoxia Ji, Yilmaz B., Warzywoda J., Sacco A. Hydrothermal synthesis of titanosilicate ETS-10 using Ti(SO₄)₂. Microporous and Mesoporous Materials. 2005. Vol. 81, Iss. 1-3. pp. 1–10.
12. Th akkar J., Wissler B., Dudenas N., Xinyang Yin, Vailhe M. et al. Recovery of Critical Rare-Earth Elements Using ETS-10 Titanosilicate. Industrial and Engineering Chemistry Research. 2019. Vol. 58, Iss. 25. pp. 11121–11126.
13. Celestian A. J., Chappell C. J., Rucks M. J., Norris P. Structure Determination and Time-Resolved Raman Spectroscopy of Yttrium Ion Exchange into Microporous Titanosilicate ETS-4. Inorganic Chemistry. 2016. Vol. 55, Iss. 21. pp. 11057–11063.
14. Kostov-Kytin V., Ferdov S., Kalvachev Yu., Mihailova B., Petrov O. Hydrothermal synthesis of microporous titanosilicates. Microporous and Mesoporous Materials. 2007. Vol. 105, Iss. 3. pp. 232–238.
15. Kalinkin A. M., Kalinkina E. V., Vasileva T. N. Effect of mechanical activation on sphene reactivity. Colloid Journal. 2004. Vol. 66, No. 2. pp. 160–167.
16. Mayorov V. G., Nikolaev A. I., Zilberman B. Ya. Radium deposition from solutions with high calcium chloride content. Tsvetnye Metally. 2007. No. 5. pp. 79–81.
17. Šepelák V., Bégin-Colin S., Le Caër G. Transformations in oxides induced by high-energy ball-milling. Dalton Transactions. 2012. Vol. 41, Iss. 39. pp. 11927–11948.
18. Fedorov S. G., Brylyakov Yu. E., Gerasimova L. G., Alekseev A. I., Galinurova L. A., Vasileva N. Ya., Plakhin V. F. Method of preparing atmosphere-resistant pigment from sphene concentrate. Patent RF, No. 2177016. Applied: 14.06.2000. Published: 20.12.2001.
19. Michel D., Mazerolles L., Berthet P., Gaffet E. Nanocrystalline and amorphous oxide powders prepared by high-energy ball-milling. European Journal of Solid State and Inorganic Chemistry. 1995. Vol. 32, Iss. 7-8. pp. 673–682.
20. Begin-Colin S., Le Caër G., Zandona M., Bouzy E,. Malaman B. Influence of the nature of milling media on phase transformations induced by grinding in some oxides. Journal of Alloys and Compounds. 1995. Vol. 227, Iss. 2. pp. 157–166.
21. Fang Zhou, Louxiang Wang, Zhenghe Xu, Qingxia Liu, Ruan Chi. Reactive oily bubble technology for flotation of apatite, dolomite and quartz. International Journal of Mineral Processing. 2015. Vol. 134. pp. 74–81.
22. Kuzmich Yu. V., Gerasimova L. G., Shchukina E. S. Structural transformations of TiO₂ during mechanical activation and subsequent annealing. Inorganic Materials. 2020. Vol. 56, No. 2. pp. 156–163.
23. Eremin V. V., Kargov S. I., Uspenskaya I. A., Kuzmenko N. E., Lunin V. V. Fundamentals of physical chemistry : Textbook. 5^th enlarged and revised edition. Moscow : Binom. Laboratoriya znaniy, 2019. Iss. 1. 351 p.
24. Tyumeneva T. Yu., Kogtenkov A. S., Lukina N. F., Chursova L. V. Advances in the development of adhesives and technologies for manufacturing mechanical rubber parts of aircraft. Polymer Science, Series D: Glues and Sealing Materials. 2014, Vol. 7, No. 2. pp. 115–117.
25. Lukina N. F., Dementeva L. A., Petrova A. P., Serezhenkov A. A. Structural and high-temperature adhesive. Aviatsionnye materialy i tekhnologii. 2012. Special issue. pp. 328–335.
26. Kablov E. N. Strategical areas of developing materials and their processing technologies for the period up to 2030. Aviatsionnye materialy i tekhnologii. 2012. Special issue. pp. 7–17.
27. Chuppina S. V., Zhabrev V. A. Organosilicates. Saint-Petersburg : Liteo, 2016. 182 p.