This study explores the intensification of molybdenite concentrate processing through a synergistic hydrometallurgical approach using sulfuric acid, nitric acid, and their combination to enhance leaching efficiency while minimizing environmental impact. Molybdenum, a strategic metal widely used in advanced engineering and catalytic systems, presents extraction challenges due to the refractory nature of molybdenite (MoS₂). The experimental approach incorporated oxygen sparging and mechanoactivation to improve dissolution kinetics and molybdenum availability. A central composite design (CCD) of response surface methodology (RSM) was employed to develop a predictive model for optimizing the leaching parameters. Acid concentration, temperature, and leaching time were systematically varied, allowing for the identification of statistically significant factor interactions and optimal operating conditions. The model demonstrated strong predictive capability with high adjusted and predicted R² values, validating its suitability for process optimization. Optimal leaching conditions were identified as 50 g/dm³ HNO₃ + 200 g/dm³ H₂SO₄, a temperature of 95 °C, a leaching time of 240 min, and a solid-to-liquid ratio of 1:6, resulting in a maximum molybdenum extraction efficiency of 72.6%. This performance was attributed to enhanced oxidative decomposition and stable complexation of molybdenum species. This study provides a scalable and environmentally conscious framework for molybdenum extraction, with implications for sustainable metallurgy and industrial applications.

The growing global demand for lithium, driven by its pivotal role in battery production, highlights the need for alternative technologies to recover this metal from low-grade and anthropogenic raw materials. This study investigates lithium extraction from aluminosilicate tailings of rare-metal production by sulfate roasting with concentrated sulfuric acid, followed by aqueous and hydrochloric acid leaching. Mineralogical analysis confirmed lithium mainly in muscovite and biotite (isomorphic substitutions) and partly as spodumene within the aluminosilicate matrix. The optimal parameters of thermochemical treatment were determined as 300 °C for 1 h at a liquid-to-solid ratio of 1:6. Subsequent aqueous leaching (90 °C, 1 h, L/S = 6:1) achieved a lithium recovery of 82.3%, while HCl proved less effective. Using response surface methodology (RSM) and a central composite design (CCD), a regression model was developed predicting up to 93.4% lithium extraction at 90 °C, a liquid-to-solid ratio of 10:1, and a leaching duration of 75 min. The calculated values showed good agreement with experimental data obtained at 90 °C, L/S = 10:1, and 30 min leaching, yielding 91.92% lithium recovery. These results confirm the efficiency of the proposed thermochemical approach and provide a scientific foundation for its further development and industrial scale-up.

Depletion of reserves of rich copper–porphyry ore deposits necessitates the development of highly efficient methods for Mo (VI) extraction from complex, corrosive hydro-metallurgical media. The present study undertakes a comprehensive assessment of sorptive concentration of Mo (VI) from strongly acidic sulfate solutions (120 g/L H₂SO₄) by employing a spectrum of commercially available strong- and weak-base anion-exchange resins. It has been established that the macroporous weak-base anion exchanger Purolite A-100 demonstrates decisive superiority over gel-type analogs (Lewatit M-800, AB-17), facilitating unimpeded intra-gel diffusion of bulky molybdenyl sulfato-complexes anions, thereby circumventing the obstructive “sieve effect.” Thermodynamic and kinetic investigations revealed that the sorption process exhibits pronounced concentration- and pH-dependent characteristics. Peak extraction efficiency (up to 95.91%) is achieved at pH ≈ 1, a finding that correlates with the region of maximal protonation of tertiary amino groups within the resin matrix. Kinetic acceleration of mass transfer upon heating to 80 °C has been experimentally confirmed, yielding 94.6% extraction within 60 min. The obtained results corroborate the prospective integration of macroporous weak-base anion exchangers into operational hydro-metallurgical schemes as an environmentally benign and efficacious alternative to conventional solvent extraction of molybdenum.

Recovery of scandium from chloride-bearing process liquors formed during titanium–magnesium production remains constrained by trace-level metal content and chemically aggressive solution matrices. Within the present study, the retention behaviour of Sc³⁺ species in strongly acidic chloride media was examined through batch-mode interaction with gel-type sulfonated cation exchangers, namely KU-2-8, Lewatit SP112H, Purosorb SAC140H, and Purolite C-150H. Quantitative evaluation of sorption efficiency was performed by calculating equilibrium uptake (q_e), phase distribution factor (K_d), and percentage recovery (R). Under identical liquid–solid ratios, the Lewatit SP112H matrix exhibited superior affinity toward dissolved scandium, achieving q_e = 179.82 mg/g and K_d = 172.41 mL/g. Equilibrium fitting procedures revealed that scandium uptake by Purosorb SAC140H conforms to monolayer-type retention described by the Langmuir formalism (R² = 0.9786), whereas sorption on Lewatit SP112H proceeds over energetically non-uniform sites and is more adequately represented by Freundlich and Dubinin–Radushkevich approximations. The observed retention characteristics establish a selection framework for ion-exchange media applicable to scandium concentration from acidic chloride hydrometallurgical streams.

Nitric–sulfuric acid leaching of substandard molybdenite concentrate from the Aktogay deposit (Kazakhstan) transfers only part of the molybdenum into solution: under the baseline process conditions, approximately 30% of the sulfide is oxidized, while roughly 70% of the molybdenum remains in the leach cake as unoxidized molybdenite. Molybdenum is thus distributed between two technologically dissimilar streams—the solution and the solid cake—and complete recovery requires processing of both. In the present work, both branches are combined into a single integrated scheme applied to a common feedstock. In the first (sorption) branch, molybdenum is concentrated from the solution. Among four anionites tested (Purolite A-100, Amberlite IRA-95, AV-17-8, and Lewatit M-800), Amberlite IRA-95 exhibited the best performance (sorption 84.21%, desorption with ammonia solution 82.15%, and selectivity coefficients Mo/Cu = 304.7 and Mo/Fe = 192.2). To remove iron, copper, and silicon impurities prior to concentration, a two-stage scheme is proposed incorporating preliminary impurity sorption on KU2-8 cationite (separation coefficients Mo/Cu = 5.7, Mo/Fe = 3.58, Mo/SiO₂ = 2.17). In the second (roasting) branch, the cake is processed: the cake, granulated with molasses, is subjected to oxidative roasting at 600 °C for 150 min under an oxygen flow (2 dm³/min) until complete desulfurization is achieved, after which the calcine is leached with ammonia. Both streams converge into a single product: the ammoniacal desorbate from the sorption branch and the alkaline solution from the calcine are acidified with nitric acid to pH 2–3, ammonium paramolybdate is precipitated by evaporation, and the precipitate is calcined to molybdenum trioxide. The resulting MoO₃, according to XRD data, is represented predominantly by orthorhombic α-MoO₃ (molybdite). Overall, the proposed two-branch scheme closes the molybdenum material balance for the substandard concentrate from both sides and outlines a technically straightforward pathway for bringing stockpiled technogenic raw material into processing.

The development of multilayer coatings based on titanium carbides and nitrides remains one of the most active areas in materials science, owing to their ability to markedly enhance wear resistance and extend the service life of machine components. Particular interest is currently focused on tailoring conventional TiN/TiCN architectures through alloying metal additions. In this study, the tribological and mechanical performance of aluminum- and zirconium-doped TiN/TiCN multilayer coatings deposited by direct-current magnetron sputtering onto 41Cr4 steel was investigated. The morphology, elemental distribution, and phase constitution of the multilayer coatings were examined. It is shown that increasing the number of bilayers from two to four in TiN/TiCN–based multilayer coatings leads to improved tribomechanical characteristics. It was determined that zirconium provides a more pronounced beneficial effect than aluminum. The four-bilayer TiZrN/TiZrCN coating simultaneously exhibited the lowest coefficient of friction (0.11) and wear rate (10⁻⁶ mm³ m⁻¹ N⁻¹) at a hardness of 16.4 GPa.