A hydrometallurgical technology for processing a titanomagnetite concentrate is proposed and substantiated. The technology includes the decomposition of the concentrate in a weakly concentrated sulfuric acid solution in the presence of a sulfonic cation-exchange resin in the H + form with the transition of the major portion of metals of the titanomagnetite concentrate to the sorbent and the formation of an ilmenite-enriched residue; the desorption of metals from the saturated sulfonic cation-exchange resin with a 5 M solution of sodium chloride; the fractional hydrolytic precipitation and separation of titanium hydroxide, iron hydroxide enriched in vanadium, pure iron hydroxide, and a mixture of iron and manganese hydroxides; and the regeneration of the sulfonic cation-exchange resin. The optimum parameters of the particular processes are determined. Sulfuric acid is weakly consumed and no liquid wastes are formed in the technology.

Представлены результаты исследований по разработке технологий утилизации кремнезолей, образующихся при переработке эвдиалитового концентрата методом сорбционной конверсии. В качестве перспективных направлений предложены и изучены: дополнительное извлечение содержащихся в кремнезолях ценных металлов сорбцией сульфокатионитом; разделение кремнезоля на обогащенный кремнеземом кремнегель и обедненный кремнеземом кислотный раствор последовательным замораживанием и размораживанием исходного кремнезоля; использование содержащегося в кремнезолях кремнезема для получения волластонита. Найдено, что из кремнезолей, полученных при 80 °С - оптимальной температуре разложения эвдиалитового концентрата методом сорбционной конверсии - сульфокатионитом может быть поглощено из содержащихся в кремнезолях, %: 58.6-70.3 Ti, 46-50 Zr, 24.7-29.9 Hf, 23.5-34.7 Nb; при этом натрий остается в кремнезоле. Низкая степень заполнения сорбционной обменной емкости сульфокатионита позволяет его дополнительно насыщать в процессе сорбционной конверсии. Показано, что в кремнегелях, полученных при последовательном замораживании и размораживании кремнезолей, концентрация SiO2 достигала 33.0 г/л. Удельная эффективная радиоактивность кремнегелей мала, что позволяет их использовать в производстве строительных материалов гражданского назначения. В обедненные кремнеземом кислотные растворы, объем которых составлял 72.5-81.2 % объема исходных кремнезолей, попадает до, %: 78.3 Ti, 56 Zr, 45.1 Hf, 76.4 Nb, 92.2 Na, 100 Th, 100 U и лишь 1.1-3.6 SiO2. Такие растворы после дополнительного укрепления пригодны для повторного использования для разложения эвдиалитового концентрата. Экспериментально доказана возможность получения волластонита из кремнезоля на основе азотнокислого раствора без использования автоклавного оборудования. Обсуждаются пути регенерации маточного раствора, полученного после осаждения прекурсора волластонита. The results of studies on the development of technologies for the utilisation of silica sols formed during eudialyte concentrate processing by means of sorption conversion are presented. As promising areas, the following directions have been proposed and studied: additional extraction of valuable metals from silica sols by sorption with sulphocationite; silica sol separation into silica-enriched silica gel and silica-depleted acid solution by successive freezing and thawing of the initial silica sol; the use of silica contained in silica sols to obtain wollastonite. The percentage of rare metals that can be absorbed by sulphocationite from silica sols obtained at a temperature of 80°C - the optimum temperature for the decomposition of eudialyte concentrate by sorption conversion - is found to be (%) 58.6-70.3 Ti, 46-50 Zr, 24.7-29.9 Hf, 23.5-34.7 Nb, while sodium remains in silica sol. The low degree of filling of the sorption exchange capacity of the sulphonic cation exchanger allows it to be additionally saturated in the process of sorption conversion. It is shown that the concentration of SiO2 reached 33.0 g/L in silica gels obtained by successive freezing and thawing of silica sols. The specific effective radioactivity of silica gels is low, which allows them to be used in the production of civil building materials. Acid solutions depleted in silica, the volume of which was 72.5-81.2 % of the volume of the initial silica sols, contain up to (%) 78.3 Ti, 56 Zr, 45.1 Hf, 76.4 Nb, 92.2 Na, 100 Th, 100 U, and only 1.1-3.6 SiO2. Such solutions after additional strengthening are suitable for reuse for the decomposition of eudialyte concentrate. The possibility of obtaining wollastonite from silica sol based on nitric acid solution without the use of autoclave equipment has been experimentally proven. The ways of regeneration of the mother liquor obtained after precipitation of the wollastonite precursor are discussed.

С целью развития технологии переработки эвдиалитового концентрата, основанной на применении метода сорбционной конверсии, исследованы закономерности извлечения металлов из насыщавшихся в процессе сульфокатионитов, а также регенерация сульфокатионита и используемых для десорбции растворов для повторного применения. Приведены составы насыщенных сорбентов, в которых содержатся щелочные (натрий, калий), щелочноземельные и редкоземельные металлы, титан, цирконий (гафний), ниобий (тантал), алюминий, железо, марганец, природные радионуклиды. Исследована десорбция различными растворами. Установлено, что наиболее трудно десорбируется ниобий (тантал). Рекомендовано проводить двухстадийную десорбцию при температуре 20 °С: сначала десорбцию раствором 5 М NaCl, при которой достигается перевод в раствор большинства содержащихся в сорбенте металлов, а затем десорбцию циркония и ниобия раствором 1 М Н2С2О4. Рассмотрены вопросы дальнейшей переработки полученных десорбатов. В соответствии с проведенными ранее исследованиями из десорбатов на основе раствора 5 М NaCl дробной нейтрализацией сначала до рН 4 осаждается и отделяется примесный кек, содержащий торий, железо, алюминий, титан, затем до рН 7.5 - концентрат редкоземельных элементов и, наконец, при рН ≥ 10 - щелочноземельные металлы и марганец. Из десорбатов на основе раствора 1 М Н2С2О4 нейтрализацией NaOH до рН 10 осаждается цирконий (гафний)-ниобиевый концентрат, из которого раствором Na2CO3 выщелачивается цирконий (гафний). Отмечено, что после десорбции раствором 1 М Н2С2О4 получается сорбент в Н+-форме, что позволяет его использовать повторно для разложения эвдиалитового концентрата методом сорбционной конверсии. Показано, что раствор 1 М Н2С2О4 может быть регенерирован методом электродиализа из раствора Na2С2О4, полученного при осаждении коллективного цирконий (гафний)-ниобиевого концентрата. In order to develop the technology of eudialyte concentrate processing based on the use of sorption conversion, the patterns of metal extraction from sulphocationites saturated in the process and the regeneration of sulphocationite and solutions used for desorption for reuse are investigated. The compositions of saturated sorbents containing alkaline metals (sodium, potassium), alkaline earth and rare earth metals, titanium, zirconium (hafnium), niobium (tantalum), aluminium, iron, manganese, natural radionuclides are presented. Desorption with various solutions is investigated. It is found that niobium (tantalum) is most difficult to desorb. It is recommended to carry out two-stage desorption at a temperature of 20 oC: at first, desorption with a 5 M NaCl solution, in which the majority of metals contained in the sorbent are converted into solution, and then desorption of zirconium and niobium with a 1 M Н2С2О4 solution. The issues of further processing of the obtained desorbates are considered. In accordance with previous studies, the impurity cake containing thorium, iron, aluminium, titanium is precipitated and separated from desorbates based on a 5 M NaCl solution through fractional neutralization, initially to pH 4, then the concentrate of rare earth elements is separated by neutralization to pH 7.5, and, finally, at pH ≥ 10, alkaline earth metals and manganese. Zirconium (hafnium) - niobium concentrate is precipitated from desorbates based on 1 M Н2С2О4 solution through neutralization with NaOH to pH 10, and then zirconium (hafnium) is leached from it using Na2CO3 solution. It is stressed that the sorbent in the H+-form is formed after desorption with a 1 M Н2С2О4 solution, which allows using it repeatedly to decompose eudialyte concentrate by sorption conversion. It is shown that the 1 M Н2С2О4 solution can be regenerated by electrodialysis from the Na2С2О4 solution obtained by precipitation of the collective zirconium (hafnium) - niobium concentrate.

The results of studies on the development of technologies for the utilisation of silica sols formed during eudialyte concentrate processing by means of sorption conversion are presented. As promising areas, the following directions have been proposed and studied: additional extraction of valuable metals from silica sols by sorption with sulphocationite; silica sol separation into silica-enriched silica gel and silica-depleted acid solution by successive freezing and thawing of the initial silica sol; the use of silica contained in silica sols to obtain wollastonite. The percentage of rare metals that can be absorbed by sulphocationite from silica sols obtained at a temperature of 80 C-degrees - the optimum temperature for the decomposition of eudialyte concentrate by sorption conversion - is found to be (%) 58.6-70.3 Ti, 46-50 Zr, 24.7-29.9 Hf, 23.5-34.7 Nb, while sodium remains in silica sol. The low degree of filling of the sorption exchange capacity of the sulphonic cation exchanger allows it to be additionally saturated in the process of sorption conversion. It is shown that the concentration of SiO2 reached 33.0 g/L in silica gels obtained by successive freezing and thawing of silica sols. The specific effective radioactivity of silica gels is low, which allows them to be used in the production of civil building materials. Acid solutions depleted in silica, the volume of which was 72.5-81.2 % of the volume of the initial silica sols, contain up to (%) 78.3 Ti, 56 Zr, 45.1 Hf, 76.4 Nb, 92.2 Na, 100 Th, 100 U, and only 1.1-3.6 SiO2. Such solutions after additional strengthening are suitable for reuse for the decomposition of eudialyte concentrate. The possibility of obtaining wollastonite from silica sol based on nitric acid solution without the use of autoclave equipment has been experimentally proven. The ways of regeneration of the mother liquor obtained after precipitation of the wollastonite precursor are dis-cussed.

The results of research on the development of the scientific foundations of the complex technology of processing Lovozersky eudialyte concentrate are summarized. The features of the concentrate composition are reported. The regularities of concentrate decomposition by sorption conversion with low-concentration solutions of mineral acids, desorption of metals from sulfocationite, stepwise hydrolytic deposition from eluates of concentrates of rare elements, the use of silicic acid transferred to solutions with simultaneous recirculation of acid solutions were studied. The outlines of the technology of complex processing of eudialyte concentrate are outlined, which provides for the production of concentrates of rare metals and the use of the main part of the silica and alkali metals contained in the concentrate.

A technology is proposed for processing of apatite concentrates by decomposition by phosphoric acid at 20°C in the presence of a sulfonic cation-exchange resin, defluorination of the obtained phosphoric acid, desorption of the sorbed cations with concentrated solutions of alkali metal salts, sequential hydrolytic precipitation of the thorium-enriched impurity cake and nonradioactive concentrate of carbonates of rare-earth and alkaline-earth elements, and regeneration of the sulfonic cation cation-exchange resin from the Na + form to the H + form. It is shown that the technology is also applicable for the processing of apatite concentrate with a high content of rare-earth elements and strontium. The technology ensures the recovery of all valuable components into commercial products while minimizing the consumption of reagents and energy, the amount of generated waste, and the environmental pollution.

Проанализированы результаты исследований по изменению при термообработке химического состава и структуры модифицированного гидроксида титана. Показано, что при нагревании во всех случаях сначала образуется анатаз, который при повышении температуры или/и продолжительности термообработки переходит в рутил. Температура начала перехода анатаз - рутил зависит от вида модифицирующего компонента. Переход происходит не скачком при определенной температуре, а постепенно в широком интервале температур, при этом одновременно могут существовать оба соединения. При постоянной температуре доля рутила возрастает с увеличением продолжительности термообработки. На основании проведенных исследований заключено, что в присутствии модифицирующих компонентов образцы диоксида титана представляют собой широкие классы нестехиометрических соединений с разной кристаллической структурой и переход анатаз - рутил не является полиморфным превращением I рода, а является следствием протекания различных химических процессов, включающих выделение анионных и/или катионных примесей в газовую или твердую фазу. The results of studies on changes in the chemical composition and structure of doped titanium hydroxide during thermal treatment are analysed. It is shown that anatase is formed at first under heating in all cases, and with further increase in temperature or in the duration of thermal treatment it is transformed into rutile. The temperature of the start of anatase-rutile transition depends on the type of doping component. The transition proceeds not abruptly at a certain temperature but gradually over a wide temperature range, while both compounds can exist simultaneously. At a constant temperature, the proportion of rutile increases with an increase in the duration of thermal treatment. It is concluded on the basis of the conducted studies that the samples of titanium dioxide in the presence of doping components represent the broad classes of non-stoichiometric compounds with different crystal structures, and the transition of anatase to rutile is not a polymorphic transformation of the 1st kind but it is a consequence of various chemical processes involving the release of anionic and/or cationic impurities into the gas or solid phases

Abstract—A technology is proposed to process ancylite-containing raw materials—ore or concentrate. The technology is based on their decomposition with 1 wt

The results of studies on changes in the chemical composition and structure of doped titanium hydroxide during thermal treatment are analysed. It is shown that anatase is formed at first under heating in all cases, and with further increase in temperature or in the duration of thermal treatment it is transformed into rutile. The temperature of the start of anatase-rutile transition depends on the type of doping component. The transition proceeds not abruptly at a certain temperature but gradually over a wide temperature range, while both compounds can exist simultaneously. At a constant temperature, the proportion of rutile increases with an increase in the duration of thermal treatment. It is concluded on the basis of the conducted studies that the samples of titanium dioxide in the presence of doping components represent the broad classes of non-stoichiometric compounds with different crystal structures, and the transition of anatase to rutile is not a polymorphic transformation of the 1st kind but it is a consequence of various chemical processes involving the release of anionic and/or cationic impurities into the gas or solid phases.

It is proposed to process a titanium magnetite concentrate containing an increased concentration of titanium dioxide by 2–4 wt. % sulfuric acid solution in the presence of sulfocationite. Under optimal conditions, 85–87 % of the concentrate decomposes and ilmenite-based residues with an increased titanium content are obtained. The main part of the dissolved iron, titanium and vanadium is absorbed by the sorbent.

The influence of the sorption conversion conditions for the eudialyte concentrate in low-concentration nitric and hydrochloric acid solutions (concentration and consumption of acid, temperature and duration of the process, sorbent consumption) on the valuable metals extraction efficiency (zirconium, hafnium, niobium, rare earth elements, titanium, manganese) into sulphocationite was studied. Optimal conditions for the process have been determined. It has been shown that sorption conversion in nitric acid solutions is more effective for separating valuable components from the silica component of eudialyte concentrate compared to both the traditional method decomposition by nitric acid and the method of sorption conversion in sulfuric and hydrochloric acid environments. The reasons for the loss of valuable metals and the behavior of natural radionuclides are discussed.

In order to develop the technology of eudialyte concentrate processing based on the use of sorption conversion, the patterns of metal extraction from sulphocationites saturated in the process and the regeneration of sulphoca-tionite and solutions used for desorption for reuse are investigated. The compositions of saturated sorbents con-taining alkaline metals (sodium, potassium), alkaline earth and rare earth metals, titanium, zirconium (hafnium), niobium (tantalum), aluminium, iron, manganese, natural radionuclides are presented. Desorption with various solutions is investigated. It is found that niobium (tantalum) is most difficult to desorb. It is recommended to carry out two-stage desorption at a temperature of 20 degrees C: at first, with a 5 M NaCl solution, in which the majority of metals contained in the sorbent are converted into solution, and then desorption of zirconium and niobium with a 1 M H2C2O4 solution. The issues of further processing of the obtained desorbates are considered. In accordance with previous studies, the impurity cake containing thorium, iron, aluminium, titanium is precipitated and sepa-rated from desorbates based on a 5 M NaCl solution through fractional neutralization, initially to pH 4, then the concentrate of rare earth elements is separated by neutralization to pH 7.5, and, finally, at pH >= 10, alkaline earth metals and manganese. Zirconium (hafnium) - niobium concentrate is precipitated from desorbates based on 1 M H2C2O4 solution through neutralization with NaOH to pH 10, and then zirconium (hafnium) is leached from it using Na2CO3 solution. It is stressed that the sorbent in the H+-form is formed after desorption with a 1 M H2C2O4 solution, which allows using it repeatedly to decompose eudialyte concentrate by sorption conversion. It is shown that the 1 M H2C2O4 solution can be regenerated by electrodialysis from the Na2C2O4 solution obtained by precipitation of the collective zirconium (hafnium) - niobium concentrate.

A new method of purification of rough sphene concentrate from phosphorus impurities has been developed, based on its treatment with low-concentrated solutions of orthophosphoric or sulphuric acids in the presence of sulphocationite. It is shown that this method provides effective purification of sphene concentrate and makes it possible to increase the efficiency of the technology through significant reduction of the consumption of acids, elimination of the formation of liquid waste, and due to the possibility of using aluminium, which is formed during the decomposition of nepheline contained in the initial concentrate.

We have synthesized oxide composites based on tungsten-modified titanium dioxide and investigated specific features of their formation and their physicochemical, adsorptive, and photocatalytic properties. The results demonstrate that tungsten modification of TiO2 makes it possible to obtain nanopowders (7.2 to 96.7 nm in particle size) with a free specific surface area from 6.4 to 215 m(2)/g. The synthesized composites have been shown to have considerably higher adsorption capacity and photocatalytic activity (PCA) in comparison to unmodified TiO2 with the same thermal history and Degussa P-25 commercially available titanium dioxide. The materials in which tungsten is incorporated into the crystal lattice of anatase, without tungsten in the form of an individual phase, offer the highest PCA. The electrical conductivity of the composites has been shown to correlate with their PCA.

Investigation of titanium sorption by sulfocationite from acidic solutions and its desorption from sulfocationite

A new technology has been considered to process monazite concentrate by treating it by a phosphoric acid solution in the presence of strong acid cation exchange resin. The end products are a carbonate of hydroxide concentrate of rare-earth elements (REEs), orthophosphoric acid, and thorium concentrate.

We have synthesized oxide composites based on TiO 2 modified with aliovalent cations, W 6+ , Co 3+ , Cu 2+ , and Fe 3+ , in the range 5–30 wt %. Its deviation from stoichiometry is increased by active generation of Ti 3+ cations during vacuum calcination at temperatures from 500 to 800°C. The photocatalytic activity (PCA) of the composites for dye degradation reactions under illumination with visible light exceeds that of analogous samples calcined in air. The PCA of the synthesized materials is an intricate function of their composition and structure. The highest PCA, which considerably exceeds the PCA of TiO 2 of similar origin and that of the commercially available Degussa P-25 TiO 2 , is offered by the optimal compositions of the W- and Cu-modified samples for ferroin and methylene blue degradation and the Co- and Fe-modified samples for aniline degradation.