Olga B. Kotova

Mineral processing mineralogy methodologies play a crucial role in the predictive assessment of rare and critical elements in ores of ferrous, non-ferrous, noble metals, and non-metallic minerals. These assessments fundamentally guide the feasibility studies and strategic planning of raw material development projects, including the evaluation of potential substitutes for strategic materials. This study focuses on the detection, identification, and characterization of unconventional occurrence forms of critical metals in ores and rocks of diverse compositions and genesis, which contain these elements in trace amounts. An optimized suite of analytical techniques was employed to obtain reliable data, facilitating the development and refinement of physical and chemical extraction, leaching, and recovery methods for valuable metals. The capabilities of mineralogical analysis techniques for identifying and diagnosing rare earth minerals—such as members of the crandallite group and svanbergite—were demonstrated on pyrochlore-monazite-crandallite ores from the Tomtorskoye deposit and bauxite ores from the Sredny Timan deposits. It was established that rare earth metals occur both as discrete mineral phases and as isomorphic substitutions within the crystal lattices of ore-forming minerals. Examples of optimally selected analytical methods are presented and discussed. Selected analytical methods, including Raman spectroscopy and X-ray diffraction (XRD), showed excellent concordance, highlighting Raman spectroscopy’s potential as a rapid and reliable diagnostic tool for complex polymineralic materials. The study emphasizes the importance of examining poorly studied minerals with potential industrial significance. For instance, svanbergite, commonly found in these ores, shows promising applications in environmental and energy-related technologies.This research was conducted under the State Assignment of the Institute of Geology of the Komi Scientific Center of the Ural Branch of RAS.

Two types of gold‐bearing ore are identified at the Shiraldjin deposit (Kyrgyz Republic): (1) a sulfide‐rich ore (approx. 60%), containing coarse native gold particles (> 70 μm); and (2) an ore type dominated by Fe oxides and hydroxides (approx. 80%) with finely disseminated gold. The latter is considered refractory owing to its complex mineral composition and, in particular, the fine intergrowth of gold with iron and manganese phases. Impurities such as manganese (up to 10%), copper, and bismuth hinder gold extraction by conventional methods. Mineralogical studies have revealed that fine gold particles are frequently encapsulated within goethite and pyrolusite, while copper occurs both as dispersed secondary oxides (e.g., malachite, cuprite) and as sulfides (chalcopyrite, chalcocite) with intergrown textures. These minerals possess similar physical properties (e.g., density and surface characteristics), making selective separation by gravity or flotation inefficient. Technological constraints are outlined, and approaches are proposed, including a combination of gravity pre‐concentration, bacterial leaching, and selective flotation as a practical strategy for enhancing gold recovery from complex oxide ores.

The thermodynamic analysis method of chemical processing for refractory iron-titanium ores is increasingly utilized to enhance the efficiency of experimental research by reducing energy and resource consumption. Despite its growing application, the current methods for calculating the thermochemical characteristics of compounds containing many critically important metals need further refinement. This research addresses this issue by introducing improvements to the methods used for calculating thermochemical constants for irontitanium and other oxides. The study focuses on commonly found minerals such as ilmenite, magnetite, perovskite, and pseudobrookite under standard conditions. These improvements provide a solid foundation for thermodynamic analysis, specifically to identify potential phase transformations that may occur during the chemical processing of complex ores. To achieve this, a hyperbolic model was employed, which takes into account the detailed internal structure of the compounds, including the type of crystal lattice and the number of occupied positions. Using this model, the study calculated the heat capacity and entropy for compounds within the Fe–Ti–O system and developed a curve that shows how heat capacity varies with temperature. Moreover, a new method was proposed for calculating the standard enthalpy of formation of these oxides. These refined calculation methods offer more accurate empirical data for iron-titanium and other oxides and can predict the heat capacity and standard enthalpy of formation for less well-studied compounds. When comparing the new calculations to reference data, the results showed good convergence, with relative errors for heat capacity, entropy, and standard enthalpy of formation at about 1.4 %. This accuracy is significantly better than that of the traditional additive methods, showing a 20-fold improvement. The calculation methods proposed in this research provide a straightforward and reliable means of thermodynamic analysis for understanding phase transformations. They have the potential to significantly advance energy- and resource-efficient technologies in mineral processing, applicable to both natural exogenous-hypergene environments and the processing of refractory iron-titanium ores.This research was conducted under the State Assignment of the Institute of Geology of the Federal Research Center Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences.

Рассмотрена возможность создания новых сорбционных материалов на основе карбонизированных промышленных отходов и вторичных продуктов переработки природного сырья для извлечения органических и неорганических токсикантов из водных сред. Изучены явления сорбции–десорбции урана-238 и микотоксина Т-2 на карбонизированных органоминеральных сорбентах. Предложены перспективные направления практического использования разработанных сорбционных углеродных материалов.

Показаны возможности комплексной оценки твердых полезных ископаемых методами технологической минералогии. Акцентировано внимание на научно-методическом сопровождении минералогических исследований, требованиях к минералогической информации, необходимых при оценке минерального сырья.

Technological mineralogy of titanium ores is the basis for assessing their complexity. It enables, from a unified standpoint, to trace the entire course of changes in mineral matter through operating procedures, including beneficiation, processing, and obtaining target industrial products. The study targets are Pizhemskoye ilmenite-leucoxene sandstones, which are distinguished by a complex polymineral composition. Along with the main ore components, there are other metals with different speciation (isomorphic admixture, independent mineral phases). The optimal set of mineralogical analysis methods for the predictive assessment of their further use is substantiated exemplified by titanium ores of the Pizhemskoye deposit, which are complex, noted for a variable content of iron oxides and contain rare earth metals. Examinations by X-ray phase analysis and scanning electron microscopy confirm that the main titanium phases of sandstones are pseudorutile and a polymineral aggregate, “leucoxene”. Considering the granulometric peculiarities of the magnetic and non-magnetic fractions of the gravity concentrate, the prospects of technologies for processing titanium raw materials are discussed. Along with the problems of obtaining high-quality raw materials, the transformations of mineral phases as a result of extreme impacts and their physicochemical properties as a consequence of isomorphic substitution of a part of Ti atoms with natural modifier agents (Fe and V) in the synthesis of titanium oxide nanostructures for industrial applications are considered (photocatalytic nanoreactor).

DOI: 10.31897/PMI.2022.43 The growing demand for mullite raw materials, which meet industrial requirements originates the search for new and alternative sources, as well as efficient technologies for obtaining the target products (nanocomposites). The article suggests a method for obtaining mullite from kaolinite experimentally (Vezhayu-Vorykvinsky deposit, Russia)....