The growing adoption of electric vehicles is expected to result in a significant increase in the volume of spent lithium-ion batteries (LIBs), highlighting the need for efficient and environmentally sustainable recycling methods. This study presents an optimized process for recovering critical metals—cobalt, nickel, manganese, and lithium—from spent LIBs. The method involves roasting followed by leaching using a deep eutectic solvent (DES) composed of propionic acid (PA), choline chloride (ChCl), and nitrilotriacetic acid (NTA), a chelating agent. Key operational parameters—including roasting temperature and duration, ChCl–PA molar ratio, leaching temperature and time, solid-to-liquid ratio, and NTA concentration—were systematically investigated. Roasting at 200 °C for 2 h improved leaching efficiencies of nickel and cobalt by 20.2% and 6.3%, respectively. Optimal leaching conditions were identified as 80 °C for 120 min with a solid-to-liquid ratio of 15 g/L. The addition of 0.07 M NTA shortened the leaching time from 120 to 60 min while achieving leaching efficiencies of 98.5% for lithium and 100% for cobalt, nickel, and manganese. Manganese was selectively separated from the leachate using D2EHPA, while cobalt, nickel, and lithium were subsequently recovered from the manganese-free solution using Cyphos IL 104 and oxalic acid. Leaching efficiency declined by 10–15% with each reuse of the DES. Overall, this approach offers a highly efficient and economically feasible strategy for metal recovery from spent LIBs, contributing to circular economy practices and sustainable battery waste management.
Egypt’s agriculture relies on imported potassium fertilizers for logistical and financial reasons. A promising local alternative is glauconite from El Gedida, Western Desert. This study presents an integrated characterization using XRD, XRF, TGA/DTA, FTIR, SEM-EDX, optical thin-section microscopy and particle size analysis. XRF revealed K2O (5.824%), Fe2O3 (25.06%), and SiO2 (40.65%), with minor Al2O3 and MgO. XRD confirmed glauconite as the main phase, while FTIR indicated hydroxyl and silicate groups. TGA/DTA showed dehydroxylation and stability up to 800 °C. SEM-EDX images highlighted a porous, flake-like morphology. Petrographic analysis described grain morphology and contacts essential for evaluating liberation behavior. Semi-quantitative XRD indicated the run-of-mine contains ~49% glauconite, with quartz (26.3%) and talc (24.7%) as major gangues. Beneficiation by wet high-intensity magnetic separation (13,000 G, 7% solid/liquid ratio) improved glauconite to ~66.8% with a high yield of 88.65%. Following beneficiation, the mineralogical traits of El-Gedida glauconite highlight its potential as potassium-bearing material, justifying deeper study into its suitability as a slow-release nutrient source. However, additional potassium-release, agronomic, and environmental studies are required before practical agricultural applications can be recommended. The upgraded material may also have potential for other industrial applications.
This study combined X-ray fluorescence spectroscopy (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), mineral liberation analysis (MLA), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), and density functional theory (DFT) to characterize zinc-bearing constituents in electric arc furnace (EAF) dust from a steel plant in Hebei, China, across multiple length scales. ICP-OES gave Zn and Fe contents of 33.48 and 19.05 wt.%, respectively, in general agreement with the XRF results. Screening semi-quantification by XRD-RIR indicated that the relative contents of the Zn-bearing Fe-based spinel-type oxide group, ZnO, and KCl among the identified crystalline phases were 81.3%, 15.2%, and 3.5%, respectively. Because the diffraction peaks of several spinel endmembers overlap, the first value does not represent the abundance of pure ZnFe₂O₄. MLA assigned a calculated mass fraction of 67.96 wt.% to the spinel-type Zn-Fe oxide class and 76.57% of Zn to this operational class. SEM-EDS of selected regions showed that the spinel-type Zn-Fe oxide class was dominated by Zn and Fe, whereas the Mg-bearing Zn-rich composite oxide class contained Zn, Mg, Ca, and Fe; both classes showed non-stoichiometric, multicomponent characteristics. Fine-particle attachment and agglomeration observed by SEM indicate that some coarse MLA objects may correspond to fine-grained intergrowths or agglomerates. DFT comparison of ideal ZnFe₂O₄ and ZnO structural endmembers showed that the Fe-O network contributes substantially to framework stability in the spinel model and that the two structures differ in their local atomic-force responses to vacancy perturbations. The resulting framework integrates bulk phase confirmation, particle-scale occurrence, and atomic-scale structural comparison, providing a structural basis for future activation and selective recovery of zinc-bearing phases.
Accurate segmentation of froth images is crucial for online monitoring of flotation performance. However, uneven illumination, specular highlight overlap and low-contrast edges frequently cause over-segmentation and under-segmentation when classical watershed transform is applied. In this study, an improved watershed algorithm incorporates specular highlight overlap correction and multi-directional edge constraints. First, Intuitionistic Fuzzy C-means (IFCM), adaptive thresholding and open-close morphological reconstruction are combined to extract and classify highlights into small, medium and large bubbles. An overlap-correction fusion strategy is then designed to remove spurious markers. Second, horizontal–vertical edges extracted by Laplacian of Gaussian (LoG) and ±45° edges obtained by diagonal gradient filters are merged to generate a complete constraint line. Finally, the fused markers and the edge-preserving constraint line are fed into a marker-controlled watershed, achieving robust segmentation of multi-scale froth images. Experiments on 50 on-site images from a tungsten–molybdenum flotation plant show that the proposed method yields mean Adjusted Rand Index (ARI) values of 81.85 %, 87.63 % and 91.63 % for small, medium and large bubbles, respectively, outperforming two state-of-the-art watershed variants.
This study investigates the effect of gas velocity, direction, and configuration on arch formation and collapse during bulk granular material discharge through horizontal orifices. Experiments were conducted using cold quasi-2D (250 × 50 × 5 mm) and hot scale models (cylindrical shaft, D = 300 mm, H = 500 mm) with high-speed imaging (2000 fps, 1280 × 1024) across various materials. Uniform gas flow stabilizes arches, reducing the normalized mass flow rate Zt/Z0 to 0.20 ± 0.03 at critical gas velocity ratios W1/W2≤20 and area ratios L1/L2≥0.37. Conversely, localized gas jets increase Zt/Z0 to 1.45 ± 0.05. The scientific novelty lies in developing a unified torque-balance model that, for the first time, predicts critical counter-current gas velocities Wkr across different configurations within a ±28.9% error margin (n = 3, p < 0.05). These findings provide a quantitative basis for designing industrial systems such as shaft furnaces, pneumatic conveyors, and dosing units. Future work will focus on industrial-scale validation, extension to humid or adhesive materials, and complex geometries to further optimize gas-assisted flow control.
To address the difficulties of solid-liquid partitioning in mine drainage, this research introduces a tandem hydrocyclone integrated with an overflow cap configuration. The design leverages the synergistic interaction between a wide-angle primary cone and a narrow-angle secondary stage to bolster the classification of fine particulates. Through a combination of computational fluid dynamics (CFD) and empirical validation, the sensitivity of hydrodynamic profiles and sorting efficiency to both geometric and operational variables was scrutinized. Findings reveal that a refined overflow cap geometry stabilizes the inflow environment for the downstream stage while mitigating manometric head loss in the lead unit, thereby facilitating mine water purification. Furthermore, elevated inlet pressures trigger a reduction in overflow solids recovery and a contraction of the separation cut-off point, which collectively sharpen the classification precision. Consequently, the strategic adjustment of structural and feed parameters is vital for maximizing the separation proficiency of the serial hydrocyclone system.
The "cliff-like" clogging in underground leaching uranium injection systems remains a critical technical challenge constraining production efficiency. Field observations indicate that fine suspended particles formed under acidic leaching conditions are the primary causative factors. This study systematically investigated the pressure variations and effluent turbidity patterns of silica fine suspended particles under different conditions (particle sizes: 1, 5, 30 & micro;m; concentrations: 200-800 mg/L; filter mesh sizes: 50-400 mesh; solution flow rates: 30-120 mL/min), as well as the migration and clogging mechanisms of silica particles. Experimental results demonstrated that when silica particle sizes exceed filter mesh openings, rapid formation of filter cakes on the surface causes abrupt pressure surges. When particle sizes approach or fall below mesh dimensions, particles gradually deposit in internal pores, leading to deep-seated clogging. While larger filter mesh sizes effectively intercept fine particles, they significantly accelerate clogging progression. Although increased flow rates temporarily delay surface clogging, they elevate the risk of particle migration into deeper ore layers. This study reveals the multi-mechanism coupling characteristics of silica particle clogging in underground leaching processes, providing theoretical and experimental foundations for optimizing injection parameters.
Kaolinite is widely used in papermaking, ceramics and other industries, but its high-value applications are limited by gangue minerals and lattice impurities (e.g., Fe, Ti). Flotation, a key purification technique, is hindered by conventional collectors’ poor selectivity and weak affinity. This review classifies collectors into anionic, cationic, mixed and novel types, analyzes key influencing factors (mineral interfacial properties, reagent structure, solution chemistry, process parameters) and elucidates their interaction mechanisms with kaolinite. Current research focuses on conventional kaolinite, while coal-measure kaolinite - abundant but with complex processing challenges - lacks attention. Its inefficient beneficiation stems from insufficient understanding of lattice impurity genetic characteristics, leading to non-targeted collector design. Future studies should prioritize coal-measure kaolinite, decode its lattice impurities, and use machine learning to screen targeted chelating collectors. Establishing a genetic coupling model will guide efficient flotation separation, improving kaolinite purity for high-end applications.
A systematic process mineralogy study and non-cyanide leaching tests were conducted on a lateritic gold ore. Process mineralogy analysis shows that the iron content in the ore reaches 42.60%, with a gold grade of 21.20 g/t. Gold occurs mainly as free and semi-exposed native gold (76.46%) and limonite-encapsulated gold (23.18%). The disseminated grain size of gold is fine. Gold is predominantly encapsulated by limonite and associated with pyrite, with only a small portion hosted in pyrite. Although the ore contains a high proportion of free and semi exposed gold, it exhibits poor leachability under conventional leaching conditions, as the fine gold particles are embedded and encapsulated within limonite. In consideration of the ore properties and green environmental protection requirements, a clean gold extraction process-fine grinding-ethylenediaminetetraacetic acid (EDTA) pretreatment leaching-environmentally friendly leaching agent Jinchan (JC) leaching-activated carbon adsorption-was developed. Through system optimization, the optimal process parameters were determined: grinding fineness of 85% at -0.074 mm, 0.25 g/L EDTA pretreatment for 12 h, JC leaching agent dosage of 5 g/L, 2.5 g/L CaO to adjust the pH to 12, and leaching time of 36 h. Under these conditions, the gold leaching rate increased to 97.17%, and the gold grade of the tailings decreased to 0.60 g/t. This study provides a reliable technical scheme and theoretical foundation for the efficient and environmentally friendly leaching of lateritic refractory gold deposits, as well as the green and economic development of similar mineral resources.
The aim of this paper was to study the adsorption of L-DOPA on HMDE using experimental data obtained from measurements of the differential capacitance of the double layer, the zero charge potential and the surface tension at this potential. The experimental data presented in this paper on the adsorption of L-DOPA on a mercury electrode at different concentrations and different pH values of the base electrolyte can expand the knowledge on the properties of the mixed adsorption layer formed by the tested organic substance and the components of the base electrolyte. The dependence of the differential capacity of the double layer on frequency observed in the studied systems indicates that adsorption equilibrium is not established during the lifetime of a single drop. Since the components of the base electrolyte: CH3COO- ions and CH3COOH molecules adsorb on the electrode, the lack of adsorption equilibrium in the presence of L-DOPA may be the result of competitive adsorption of ions and adsorbate molecules present in the solution.
To address the impact of turbulent interference on the stability of the flow field and separation performance of hydrocyclones, we propose a design that incorporates a helical downward structure in the feed section. This design not only mitigates turbulence but also facilitates a preclassification effect. Numerical simulations were used to investigate the impact of the downward height on the internal flow field and separation performance of a hydrocyclone. An increase in the downward height reduces the static pressure, tangential velocity, and turbulence intensity of the inner flow field of the hydrocyclone while increasing the axial velocity at the inner swirl, which improves the processing capacity of the hydrocyclone. In addition, this increase in the downward height reduces the degree of particle mismatch and improves the classification accuracy. Compared with the conventional tangential inlet hydrocyclone, the optimized helical downward hydrocyclone achieves higher separation accuracy, demonstrating distinct advantages.
This study investigates the flotation separation of chalcopyrite and pyrrhotite within a low-alkalinity environment. Single-mineral flotation tests were conducted alongside X-ray photoelectron spectroscopy (XPS) and Materials Studio simulations to systematically evaluate how calcium hypochlorite (Ca(ClO)2) enhances separation performance and alters interfacial chemical mechanisms. Initial results characterized flotation without a depressant. At a potassium amyl xanthate (PAX) dosage of 150 g/t, chalcopyrite and pyrrhotite exhibited similarly high recoveries of 90.56% and 89.24%, respectively, resulting in poor separation efficiency. Density functional theory (DFT) calculations corroborated this, revealing a marginal 0.09 eV difference in PAX adsorption energies between the chalcopyrite (-1.38 eV) and pyrrhotite (-1.29 eV) surfaces. Introducing Ca(ClO)2 significantly modified the surface properties of both minerals, widening their disparity. The maximum flotation recovery difference was achieved at 1300 g/t Ca(ClO)2 and 150 g/t PAX. Optimal conditions enriched the Cu grade to 29.12% at an 85.53% recovery, achieving a 3.83 separation index and an excellent Separation Efficiency (SE) of 72.86%. Following Ca(ClO)2 interaction, surface analyses revealed strong oxidation on the pyrrhotite surface, converting S2- and Fe2+ to SO42- and Fe3+. The subsequent accumulation of hydrophilic Fe(OH)3 and SO42- depressed pyrrhotite flotation by hindering PAX adsorption. Conversely, characteristic PAX functional groups (-CH3, -CH2-, C-O-C) remained detectable on chalcopyrite. Oxidation on chalcopyrite generated S0/Sn2- and cleaved Cu–S and Fe–S bonds, creating dangling bonds that provided additional active sites for collector interaction. Ultimately, these distinct surface modifications selectively amplified the hydrophobicity difference, providing a mechanistic foundation for the efficient separation of complex copper-sulfur ores.
South Africa produces platinum group metals (PGMs) from a UG2 ore that is also rich in chromite; the chromite is discarded as a tailings product. Since the fine dissemination of PGMs requires fine grinding to liberate the valuable metals, the products are in the fine-to-ultra-fine particle size range. The accumulation of valuable fines in tailings dams is a global phenomenon caused by a lack of adequate beneficiation methods for the fine material. Compared to gravity separation methods, flotation is more efficient for treating materials with particle sizes <100 microns but >25 microns. The current work explored the feasibility of floating chromite of -75/+25 microns and -25 microns in particle size. The zeta potential of a chromite concentrate is positive below pH 6 and negative above pH 6; the mineral liberation analysis of the UG2 tailings is reported. The investigated conditions included alkaline pH (8.5 to 10), collector dosage from 600 to 1000 g/t and four collector types. Flotinor-VF2711 and Collector-C showed great selectivity between chromite and silicates. The Cr2O3 grade was upgraded from ~12% to 20%; after one cleaning step, 25% Cr2O3 was achieved. The SiO2 grade was reduced from ~37% to 24%. For the <25 µm fraction, direct flotation under the probed conditions did not yield results; reverse flotation is recommended for the treatment of the ultra-fine chromite sample.
To address the issue of coarse particle mismatch in the overflow, this study proposes a self-adaptive hydrocyclone with overflow adjustment. By designing a conical vortex finder and a spring-loaded ball back pressure structure to achieve a size-adaptive adjustment of the vortex finder based on separation conditions. This study conducted a single-factor experiment to investigate the effects of feed pressure, feed concentration, and underflow port diameter on the separation performance of the hydrocyclone. The test results show: The centrifugal force within the hydrocyclone strengthened as the feed pressure increased, the solid yield of the underflow increased, and the separation efficiency curve shifted to the left. As the feed concentration rose, the content of coarse particles in the overflow increased, the cut size increased by 2.4 & micro;m, and the separation performance decreased significantly. The hydrocyclone exhibits a high separation efficiency when the underflow port diameter is 12 mm.
Only the performance-stable ultrafine calcium hydroxide (Ca(OH)2) suspension has industrial practical value. This study investigated the variations in particle size, morphology, crystalline phase, sedimentation, and rheological properties of three-concentration ultrafine Ca(OH)2 suspensions (prepared via wet digestion) during 120 h of static settling. The results indicated that the three concentrations of ultrafine Ca(OH)2 suspensions exhibited consistent patterns of change in particle size, morphology, crystalline phase, sedimentation, and rheological properties during the settling process. Firstly, particle size and morphology of Ca(OH)2 only changed slightly at the initial settling stage and resumed their original states with prolonged settling. Secondly, in terms of the composition of the crystalline phase and the rheological properties, it can be observed that there is no significant change during the 120 h static settling process. Finally, regarding settling characteristics, it was found that the position of the settling interface of the ultrafine Ca(OH)2 suspension was influenced by its concentration, with the settling interface of the 18.87 wt.% suspension dropping by only 8% and that of the 9.44 wt.% suspension dropping by 48%. In conclusion, the ultrafine Ca(OH)2 suspension prepared by lime wet digestion showed excellent property stability and thus possesses considerable potential for industrial applications.
The growing demand for critical raw materials and increasing environmental concerns have intensified interest in sustainable metal recovery from both primary ores and secondary resources. While conventional extraction from ores remains essential, it is often associated with high energy consumption, reagent use, and environmental impacts. In parallel, recovery from secondary sources such as electronic waste (e-waste), industrial by-products, and end-of-life products has emerged as a key strategy within urban mining and circular resource utilization. Deep eutectic solvents (DESs) have recently gained attention as tunable solvent systems due to their adjustable physicochemical properties, relatively simple preparation, and potential environmental advantages. DES-related research has increased significantly, with a notable rise in DES-based leaching studies since 2018. This review provides a comprehensive overview of DES applications in the recovery of critical and rare metals from both primary ores and secondary resources, emphasizing physicochemical properties, selective leaching behavior, operating conditions, process flowsheet considerations, and downstream recovery challenges. DESs have been applied in spent lithium-ion batteries, permanent magnets, primary ores, waste printed circuit boards (WPCBs), coal fly ash, metallurgical slags, and red mud. These studies highlight the potential of DESs for processing complex matrices and enabling selectively dissolution of target metals under specific solvent and process conditions. By integrating this review critically evaluates the scientific and practical significance of DESs in improving metal selectivity, reducing reliance on aggressive mineral acids, and supporting circular economy strategies, while identifying key challenges related to solvent stability, recyclability, downstream recovery, process integration, and scale-up.
A detailed study was performed using "DFT" calculations at the "CAM-B3LYP-D3/6-311+G (d,p)" level to investigate how H2O is captured by a ZnS, ZnTiS or ZnCrS heterocluster. The weak signal strength observed near the parallel edge of the nanocluster sample could be because of the non-spherical arrangement of the ZnS, ZnTiS or ZnCrS heterocluster caused by H/OH binding. This hypothesis about energy absorption was supported by analyzing the density distributions of "TDOS, PDOS, OPDOS, ESP" for both the bare and water-coated ZnS, ZnTiS and ZnCrS heteroclusters. An isosurface map showed a larger area involved in H2O adsorption on the ZnS, ZnTiS or ZnCrS surface, leading to the formation of a hydrated ZnS (H+OH-), ZnTiS(H+OH-) and ZnCrS (H+OH-)complexes, with specific atoms labeled as "O1, Zn15/Ti15/Cr15, O27, H29, and H30". Based on this, it could be said that the Zn/Ti/Cr in the cubic ZnS, ZnTiS or ZnCrS, respectively has a greater ability to accept electrons during H2O adsorption. It's also important to note that when all the surface elements of ZnS, ZnTiS or ZnCrS are covered by "OH-/H+" ions, the semiconducting treatment is restored. These findings suggest that the electronic properties can be adjusted by controlling the adsorption position on the ZnS, ZnTiS or ZnCrS surface. This study aims to explore methods for treating water and enhancing the effectiveness of titanium zinc sulfide and chromium zinc sulfide alloy photocatalysts in removing pollutants. The findings can potentially lead to the development of more efficient water purification processes through further research on photocatalysts.
The ongoing expansion of global industry in the 21st century has accelerated the demand for critical metals such as iron, titanium, zirconium, and hafnium. Insular coastal placer deposits have emerged as a potential supplementary resource due to their extensive distribution. Mineralogical analysis of the Hainan Insular Coastal Placer (HICP) from Hainan Island, China, revealed a quartz-dominated assemblage with highly liberated ilmenite and magnetite (Fe–Ti carriers) as well as zircon (Zr–Hf carriers). In contrast, rutile (a Ti carrier) occurred predominantly in intergrowth with other minerals. Particle size distribution analysis demonstrates titanium enrichment in the 0.074-0.15 mm fraction (52.37%), while zirconium and hafnium concentrate in finer fractions (0.0385-0.074 mm). Based on the properties of the HICP, a processing flowsheet was developed involving ‘offshore gravity separation – magnetic separation – grinding and electrostatic separation – in-situ tailing disposal, onshore flotation’. This process enabled the beneficiation of low-grade feed (Fe 1.58%, TiO2 0.25%, ZrO2 0.07%, Hf 0.001345%) into high-grade concentrates (Fe 63.02%, TiO2 40.90%, ZrO2 37.05%, Hf 0.68%). The process achieved a 93.2% tailings discharge rate through ship-based in-situ disposal, which reduces ecological impact, lowers ore transportation volume, and alleviates the burden on terrestrial tailing storage facilities. The proposed method not only enhances process efficiency but also establishes a sustainable framework for marine mineral extraction.
To address the bottleneck of inefficient separation between kaolinite and other clay minerals from coal slurry during flotation, this study systematically investigated flotation separation system employing kerosene as the collector, sec-octyl alcohol. as the frother, and polyglutamic acid (PGA) as the selective suppressant. Through flotation experiments combined with characterization techniques including Fourier Transform Infrared Spectroscopy (FT-IR), contact angle analysis, and adsorption capacity measurements, Experimental results indicate that in a weakly alkaline pulp environment, polyglutamic acid effectively suppresses kaolinite flotation while minimally affecting coal floatability. At pulp pH of 8 and polyglutamic acid dosage of 240 g/t, the clean coal yield reached 74.48% with an ash content of 6.47%. Contact angle and adsorption capacity tests further revealed the distinct adsorption characteristics of polyglutamic acid on coal and kaolinite surfaces. After polyglutamic acid treatment, the contact angle on kaolinite decreased from 17.76° to 5.16°, whereas the contact angle on coal samples remained essentially unchanged. FT-IR analysis revealed that the carboxyl groups in polyglutamic acid molecules undergo chemical adsorption with kaolinite surfaces, enhancing their hydrophilicity and effectively suppressing mechanical entrainment of kaolinite during flotation. This study confirms polyglutamic acid's potential as a highly effective selective inhibitor in coal slurry flotation, providing theoretical foundations and technical pathways for mitigating clay mineral interference in flotation processes and improving coal slurry separation efficiency.
Black shale vanadium-bearing quartzites are predominantly processed by sulfuric acid leaching with the recovery of vanadium, molybdenum, uranium, and rare earth elements, resulting in the formation of vanadium-bearing shale leaching residue. Currently, cake of leaching vanadium black shale quartzite is mainly utilized in the construction industry for the production of building materials with low added value. This study investigates the production of ferrosilicon from a mixture of autoclave leaching residue of vanadium-bearing black shale quartzites and long-flame coal beneficiation tailings. The experiments were conducted using a second-order rotatable experimental design combined with electric smelting in an electric arc furnace to determine the optimal technological parameters. The results demonstrate that ferrosilicon grades FeSi45 and FeSi50 can be obtained from leaching residue and coal beneficiation tailings depending on their ratio and the proportion of steel shavings added to the charge. The optimal parameters for producing FeSi45 with a silicon recovery of 75.0-80.1% are a tailings-to-leaching residue ratio of 1.42:1-1.7:1 and 16.7-23.05% steel shavings. For FeSi50 with a silicon recovery of 75.0-79.4%, the optimal ratio is gamma=1.44:1-1.7:1 with 14.3-17.8% steel shavings. Pilot-scale laboratory electric smelting of a charge containing 51.3% coal beneficiation waste, 30% leaching residue, and 18.7% steel shavings confirmed the feasibility of producing FeSi45 with a silicon content of 41.1-43.4% and a silicon recovery of 79% in the alloy.
