Niobium commonly occurs as a minor component in Fe–Ti–O oxide systems associated with ilmenite ores and titanium-bearing metallurgical materials, yet its speciation and incorporation mechanisms remain insufficiently resolved. This study investigates the distribution, structural incorporation, and microphase localization of niobium in the Fe–Ti–O system, with emphasis on TiO₂-rich domains. Electron probe microanalysis with EDS/WDS, X-ray diffraction, thermal analysis, and thermodynamic modeling in HSC Chemistry were combined to characterize niobium-bearing phases in natural and model oxide systems. Niobium was found to occur in two principal modes: as a low-level isomorphic impurity in Fe–Ti oxide matrices and as localized enrichments in TiO₂-rich domains, particularly rutile lamellae. A first-order area-based estimate for representative analyzed grains suggests that approximately 60–80% of the detected niobium is associated with the lamellar TiO₂ channel. The combined observations are consistent with a sequential mechanism involving isomorphic substitution of Nb in Ti sites, followed by microphase enrichment and segregation into more compositionally distinct niobium-bearing oxide or titanate microphases. In the studied material, integrated mapped-field Nb is about 0.04 wt.%, whereas matrix Nb commonly lies at trace levels of about 0.02–0.05 wt.% under the applied analytical conditions, consistent with low-level background incorporation, whereas locally Nb-enriched rutile-like domains reach about 0.70–1.00 wt.%. TiO₂-rich domains are therefore identified as the principal concentrators of niobium in Fe–Ti oxide systems. Taken together, the natural observations, model experiments, and thermodynamic calculations support an integrated mechanistic sequence of Nb evolution in the Fe–Ti–O system: isomorphic substitution → microphase enrichment in TiO₂-related domains → segregation into distinct Nb-bearing oxides/niobates. These findings provide a practical framework for interpreting Nb behavior in natural and technological Fe–Ti–O materials.

This article presents the results of a study on the processing of industrial by-products from titanium tetrachloride production for the purpose of niobium extraction. Three types of niobium-containing materials were studied: titanium chlorinator sludge, dust chamber sublimate, and molten slag from the dust-settling chamber with a salt bath. The chemical and phase compositions were investigated using SEM-EDS, XRF, and XRD methods. Niobium was found predominantly in the form of refractory oxides and complex phases. Thermodynamic modeling using HSC Chemistry confirmed the stability of niobium oxides and the possibility of chlorination to volatile chlorides in a reducing environment. Leaching experiments showed that traditional water and acid treatments (HCl, H₂SO₄) result in low niobium extraction rates (up to 26%), whereas HFcontaining solutions allow for recovery of up to 53%. Based on experimental and modeling data, optimal parameters for selective niobium extraction were established. The proposed approach enables efficient recovery of valuable rare elements and contributes to the reduction of environmental impact from titanium production residues.

В статье представлены результаты минералогического исследования ильменитового концентрата, полученного из россыпей Сатпаевского месторождения Восточно-Казахстанской области. Работа направлена на изучение распределения редких и редкоземельных элементов – ниобия, циркония, скандия, лантана и церия – в структуре концентрата. Применены методы сканирующей электронной микроскопии с энергодисперсионным анализом (SEM-EDS) и фазового моделирования в программной среде HSC Chemistry. Установлено, что элементы находятся как в виде изоморфных замещений в структуре ильменита, так и в форме микровключений в гемоильмените, гематите, псевдорутиле и титаномагнетите. Полученные данные свидетельствуют о высокой перерабатываемости сырья и целесообразности его комплексного использования с извлечением стратегически важных компонентов Мақалада Шығыс Қазақстан облысындағы Сәтпаев кен орнының шайынды кендерінен алынған ильменит концентратының минералогиялық зерттеу нәтижелері ұсынылған. Жұмыс ниобий, цирконий, скандий, лантан және церий сияқты сирек және сирек жер элементтерінің концентрат құрылымындағы таралуын зерттеуге бағытталған. Зерттеуде сканирлеуші электрондық микроскопия мен энергия-дисперсиялық талдау (SEM-EDS), сондай-ақ HSC Chemistry бағдарламалық ортасындағы фазалық модельдеу әдістері қолданылды. Элементтердің ильменит құрылымындағы изоморфты орынбасулар түрінде де, гемоильменитте, гематитте, псевдорутилде және титанмагнетитте микрокосындылар түрінде де кездесетіні анықталды. Алынған деректер шикізаттың кешенді пайда- лану және стратегиялық маңызды компоненттерді өндіру тұрғысынан жоғары өңдеуге жарамдылығын көрсетеді The article presents the results of a mineralogical study of ilmenite concentrate obtained from the placers of the Satpayev deposit in the East Kazakhstan region. The research focuses on the distribution of rare and rare-earth elements – niobium, zirconium, scandium, lanthanum, and cerium – within the structure of the concentrate. Scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) and phase modeling in the HSC Chemistry software environment were applied. It was found that the elements occur both as isomorphic substitutions within the ilmenite lattice and as micro-inclusions in hemoilmenite, hematite, pseudorutile, and titanomagnetite. The results demonstrate the high processability of the raw material and the feasibility of its comprehensive utilization with the extraction of strategically important components

Niobium can concentrate in TiCl₄ wet scrubber slurry during molten-salt chlorination of ilmenite-derived titanium slag. This study presents an engineering assessment using published Nb-routing data, characterization of an isolated slurry solid, HSC Chemistry 6 balances, process design, and techno-economic screening. The reference model combines a 58.2% slag-to-slurry Nb distribution with an independently published bulk grade of 11.6841 wt.% Nb. These inputs come from different datasets and define a scenario rather than a closed campaign balance. For slag containing 0.044 wt.% Nb₂O₅, the calculated slurry inventory is 0.179 kg Nb t⁻¹ slag and dry-intermediate yield 1.53 kg t⁻¹ slag. XRD and SEM–EDS characterize a heterogeneous isolated solid with local Nb-rich domains; laboratory preparation did not reproduce the proposed two-stage treatment. With complete assumed Nb retention, the upper-bound routing/recovery potential is 58.1%; 95% and 90% thermal-retention cases reduce it to 55.2% and 52.3%. The theoretical process-material duty is 8.02 MJ t⁻¹ slag and heating electricity 2.51 kWh t⁻¹ slag. At 30,000 t slag y⁻¹, screening CAPEX is USD 0.293 million and annualized thermal-section cost USD 2.34 t⁻¹ slag. Pilot testing is required to close the Nb balance and verify energy use and condensate composition before recovery or recycle performance can be demonstrated.