This study presents a sustainable approach for processing low-grade lithium-bearing aluminosilicate ores via carbothermic treatment with selective lithium stabilization in the slag phase. The proposed method is based on controlled phase transformations that suppress lithium volatilization and promote its retention in the condensed phases. Thermodynamic analysis revealed that lithium volatilization is unfavorable within a defined temperature window, enabling its stabilization in the slag. Experimental smelting, conducted at 1550–1600 °C with the addition of an iron-bearing component, resulted in the selective reduction of silicon and aluminum into a ferro silicon aluminum alloy, while lithium was efficiently concentrated in the slag phase. Lithium recovery to the slag reached up to 94%, with losses to the gas phase below 6%, demonstrating a significant reduction in volatilization compared to conventional high-temperature processes. X-ray diffraction (XRD) analysis confirmed that lithium is predominantly immobilized in the form of LiAlSiO₄ (pseudo-eucryptite), which enhances the chemical reactivity of the slag. From a sustainability perspective, the proposed process enables efficient utilization of low-grade lithium resources, minimizes lithium losses, and eliminates the need for energy-intensive pre-treatment steps such as roasting or vacuum processing. The resulting lithium-bearing slag represents a reactive intermediate suitable for subsequent hydrometallurgical extraction, enabling an integrated and resource-efficient process route. The results demonstrate that phase-controlled carbothermic processing is a viable and sustainable strategy for lithium recovery from low-grade aluminosilicate ores.

This study investigated the production of spodumene concentrate and lithium carbonate from a low-grade pegmatite ore containing approximately 0.26 wt.% Li₂O. The ore consisted predominantly of a quartz–feldspar aluminosilicate matrix with dispersed spodumene mineralization, which complicates conventional processing approaches. Preliminary lithium concentration was performed by dense media separation (DMS) using an industrially applicable ferrosilicon-based suspension. The highest separation efficiency was achieved for the −4.0/+2.8 mm fraction, producing a DMS concentrate containing 5.77 wt.% Li₂O with 98% lithium recovery. The obtained spodumene concentrate was subjected to decrepitation at 1000–1100 °C to convert α-spodumene into the more reactive β-modification, followed by sulfation roasting with concentrated sulfuric acid at 250–270 °C. The productive leach solution obtained after water leaching contained up to 12.1 g/L Li₂O. After purification from iron-bearing impurities and precipitation with sodium carbonate, a lithium carbonate product containing at least 98.8 wt.% Li₂CO₃ was obtained. Approximately 53% of the lithium contained in the original ore was recovered into the DMS feed fraction, whereas the overall lithium recovery into lithium carbonate reached about 45% relative to the ore and approximately 70% relative to the concentrate.

The development of efficient technologies for processing secondary technogenic raw materials represents a promising approach to replenishing vanadium resources. This study investigates the processes of sulfuric acid reductive leaching of vanadium from spent vanadium catalysts using oxalic acid and metallic iron as reducing agents. It was established that oxalic acid provides vanadium extraction of up to 95.2%, whereas the use of metallic iron (2–3 wt.% of the catalyst mass) enables a vanadium recovery rate of 91–92% at a solid-to-liquid ratio of 1:7 and pH 1.3–1.5, offering a more cost-effective alternative. Thermodynamic modeling of the V–Fe–P–SO₄–C₂O₄–H₂O system was performed using the Medusa software package over a pH range of 0–3. The results showed that vanadium(IV) predominantly exists as the VOSO₄ complex in sulfuric acid solutions, whereas the formation of oxalate and phosphate complexes is thermodynamically insignificant. Iron(III) was found to exhibit a strong affinity toward phosphate ions, promoting their selective precipitation as an iron phosphate phase while maintaining vanadium in solution. The obtained results provide a scientific basis for the efficient preliminary separation of iron and vanadium and for improving the selectivity of subsequent vanadium sorption.

An integrated hydrometallurgical process for the recovery of vanadium from spent petrochemical catalysts and the production of high-purity ammonium metavanadate (AMV) was developed and experimentally validated. Alkaline leaching of roasted vanadium-bearing catalysts resulted in vanadium extraction of 90%–95%, producing a solution containing 37.0 g/L V₂O₅ together with phosphorus, sulfur, silicon, and molybdenum impurities. Two purification approaches, ion-exchange sorption and magnesium oxide treatment, were evaluated for impurity removal. Sorption using the macro porous anion-exchange resin Biolite 200U provided effective silicon removal but resulted in significant vanadium losses (up to 19.6%) due to co-sorption of vanadium and phosphorus. In contrast, magnesium oxide treatment at 70–80 °C reduced the phosphorus concentration from 0.39 to 0.04 g/L (approximately 90% removal) and completely removed silicon while limiting vanadium losses to less than 2.5%. Following purification, ammonium metavanadate was precipitated using ammonium chloride at a V₂O₅:NH₄Cl molar ratio of 1:2 and pH 8.8–9.0, achieving approximately 99% vanadium recovery. X-ray diffraction analysis confirmed the formation of single-phase NH₄VO₃ after solution purification, whereas precipitation from untreated solutions resulted in contamination by alumina-bearing phases. The proposed process provides an effective route for producing purified ammonium metavanadate suitable for subsequent conversion into metallurgical-grade V₂O₅. The ultimate goal of the proposed technology is the production of metallurgical-grade ferrovanadium (FeV80). Because AMV is thermally converted to V₂O₅ with a weight loss of approximately 24%–25%, phosphorus and sulfur concentrations in AMV must be maintained below approximately 0.04 wt.% to ensure compliance with the impurity requirements of FeV80 according to GOST 27130-94.