Geological setting and mineral composition of (apatite)-nepheline-titanite ore from the Khibiny massif enable selective mining of titanite ore, and its processing with sulfuric-acid method, without preliminary concentration in flotation cells. In this process flow diagram, titanite losses are reduced by an order of magnitude in comparison with a conventional flotation technology. Further, dissolution of titanite in concentrated sulfuric acid produces titanyl sulfate, which, in turn, is a precursor for titanosilicate synthesis. In particular, synthetic analogues of the ivanyukite group minerals, SIV, was synthesized with hydrothermal method from the composition based on titanyl-sulfate, and assayed as a selective cation-exchanger for Cs and Sr.

In this paper, a universal technology is proposed for processing low-titanium mineral raw material—apatite-nepheline ore waste, including its treatment with sulfuric or hydrochloric acid in a two-stage mode with a sequential increase in the concentration. This technique allowed us to remove nepheline and apatite in the first stage and achieve a titanium mineral content of TiO₂ of more than 30%; in the second stage, we were able to convert the titanium into its precursors—titanyl sulfate monohydrate TiOSO₄·H₂O and a hybrid rutile-silica composition. The key stage in the sorbent synthesis is the reaction of the precursor with a phosphoric acid solution. The preferred sequence of operations begins with the mechanical activation of the precursor, causing morphological changes in it, and subsequent treatment with phosphoric acid at different concentrations under atmospheric conditions and in an autoclave, accompanied by phase transformations. Conditions for the chemical reactions which regulated the composition and structure of the final product and, accordingly, its sorption activity were found. With the help of XFA, the phase compositions of the sorbents were identified, including the individual crystalline phase α-TiP obtained from TS or the crystalline phase αTi(HPO₄)₂∙H₂O, which is in an amorphous silica matrix obtained from a rutile–silica composition.

An original method based on the use of technogenic waste from the processing of mineral-layered materials, in particular phlogopite for obtaining highly efficient functional compositions of the “mica-TiO₂”, has been developed. The composition core is a nanosized mica flake coated with mesoporous titanium dioxide of an anatase or rutile structure. Energy-saving and environmentally friendly technological methods are based on the splitting of the mica followed by heterogeneous electrohydrolysis of a mixture of titanium (IV) sulfate solution and flake particles. No destruction of the mica surface, which provided the obtained uniform coatings, has been observed. Such coatings are used in photocatalysis processes and possess a self-cleaning capability. Core–shell compositions are more economically attractive compared with titanium dioxide, in particular TiO₂ grade P25 (Degusse). The core of the transparent flake and the shell of the rutile titanium dioxide endows the final product with a pearlescent optical effect. This type of material is widely used in the manufacturing of paints and varnishes, printing inks, cosmetics, etc. The use of technogenic waste could significantly reduce the cost of the final product, which would ensure its widespread use in various industries.

The waste of apatite-nepheline ore processing was chosen as the material of study for the present investigation. The chemical and phase compositions have been analyzed and the route of the new technology has been developed. Treatment of the waste with diluted hydrochloric acid enables to separate apatite, nepheline, titano-magnetite minerals from titanite (CaSiTiO₅). The obtained titanite concentrate contains 30–32% of titanium dioxide. Interaction of titanite with hydrochloric acid under heating and stirring conditions results in calcium leaching. The titanite decomposition is accompanied by titanium and silica oxides precipitation. The resulting solid has been used as a precursor for the synthesis of functional materials. Mechanochemical activation of the precursor provides the structural and morphological disorder of the initial particles. Thermodynamic stability of activated particles is achieved by chemisorption or roasting.

The modal composition of (apatite)-nepheline-titanite ore and its geological setting within apatite deposits of the Khibiny Massif allow selective mining of titanite ore and its hydrochloric acidic processing. The reaction of titanite with concentrated hydrochloric acid produces hydrated titanosilicate precipitate (TSP) which, in turn, can be a precursor in titanosilicate synthesis. It is particularly noteworthy that a synthetic analogue of korobitsynite, Na₅(Ti₃Nb)[Si₄O₁₂]₂O₂(OH)₂·7H₂O, was synthesized by means of TSP alteration by alkaline hydrothermal solution at 200 °C within three days. The titanosilicate obtained this way has comparatively weak cation-exchange properties regarding Cs⁺ and Sr²⁺ cations and considerable photocatalytic activity occurring under visible light, which allows the use of a synthetic korobitsynite analogue (SKR) for production of self-cleaning, sterilizing, and anti-fouling building materials.

Интенсивная эксплуатация объектов гражданского и оборонного назначения рождает серьезные экологические проблемы, требующие эффективного решения. Показано, что для очистки жидких стоков от токсичных веществ могут эффективно использоваться новые сорбционные материалы специфической минералоподобной структуры. К таким материалам относятся щелочные титаносиликаты каркасной структуры с широкими каналами, которые обеспечивают высокую степень необратимого поглощения катионов, при этом устойчивы к температурному и химическом увоздействию. Разработан инновационный способ высокотемпературного гидротермального синтеза титаносиликатного прекурсора, приготовленного смешением растворов силиката натрия и сульфата титанила(IV), с получением кристаллического осадка каркасного строения со структурой минерала иванюкита – щелочного титаносиликата. Во внекаркасных каналах находятся вода и катионы натрия, способные к ионнообменным реакциям. По данным РФА исследуемый образец состоит из одной фазы, отвечающей формуле Na₃К(TiO)₄(SiO₄)₃·4-6H₂O, с кубической структурой. Синтезированный мезопористый материал представляет собой порошок, агломерированный в частицы размером 50-100 нм. Методом экструзии, без дополнительной добавки связующего, сформированы гранулы с показателем прочности – 12,5 МПа и соответственно с высокой гидравлической устойчивостью. Распределение пор по размерам рассчитывали BJH методом по кривой десорбции. Для порошка отмечено достаточно однородное распределение пор по размерам 8-18 нм, для гранул за счет агломерирования частиц характерны широкие мезопоры и макропоры с размером 10-50 нм. Изучены сорбционные свойства иванюкита в статическом и динамическом режимах. По кинетике поглощения двухзарядных катионов предложен ряд активности Co²⁺>Ni²⁺>Cu²⁺. Для гранулированного материала рассчитаны коэффициенты распределения катионов, в мл/г: Co²⁺ - 9,2∙10³; Ni²⁺ - 9,7∙10³; Cu²⁺ - 1,7∙10⁴. С использованием данных рентгеновского микрозондового анализа определено содержание Me в сорбенте после сорбции. Рассчитана степень замещения в системе Me²⁺→Me⁺, которая составляет 84-95%. Использование каркасного титаносиликатного сорбента для очистки растворов, содержащих катионы переходных металлов, может быть перспективным.