Search Results (171)

Due to its extensive industrial applications and high market prices, as well as low mining yield, the recovery of rhodium from various secondary resources is becoming increasingly urgent for addressing its supply issues. Generally, rhodium is extracted last from the leaching solutions containing other platinum group metals and base metals. The lengthy processing flow led to the inevitable yield loss of rhodium. Compared to the conventional extraction process, selective preferential separation and extraction of rhodium are of great significance for achieving its high economic value and efficient recovery. However, selective preferential separation and extraction of rhodium have to face many difficulties, such as its kinetically inert properties, being prone to hydration and hydrolysis reactions, etc. This paper reviews various promising improvements and new technologies for selective preferential separation and extraction of rhodium from mixed metal solutions, including precipitation, liquid–liquid extraction, adsorption and other emerging technologies. The advantages and disadvantages of those reported technologies were evaluated. It is pointed out that the selective preferential adsorption of rhodium based on molecular recognition and ion imprinting is a promising rhodium recovery technology, which is economical and consistent with the concept of green chemistry. Full article

Mining activities generate large volumes of waste that pose both environmental liabilities and potential secondary resource value. A significant fraction of these materials still contains recoverable copper, making leaching a promising strategy for reprocessing and valorization, given the natural decline in ore grade. This study presents a PRISMA-based systematic review of recent literature on leaching technologies applied to mining waste, with emphasis on technical performance, environmental implications, and economic feasibility. The reviewed residues include tailings, slags, copper smelter dusts, sludges, waste rock, leaching residues, and other secondary mining and metallurgical wastes. The main leaching routes identified were acidic, biological, alkaline, and hybrid systems, including conventional H₂SO₄ leaching, pressure oxidative leaching, chloride-based systems, glycine- and ammonia-based alkaline media, organic acids, deep eutectic solvents, and biologically mediated processes. Reported Cu recoveries ranged from low values in refractory systems to near-complete extraction under optimized conditions. Overall, copper recovery was controlled primarily by the mineralogical occurrence of Cu rather than by leaching category alone. In contrast, the highest recoveries were generally associated with intensified conditions capable of overcoming sulfide- and silicate-related constraints. Environmental and circular economy benefits were frequently claimed but less often demonstrated through direct evidence, while economic assessment remained limited. Future research should better integrate mineralogical interpretation, environmental verification, and economic feasibility. Full article

As lithium demand surges and primary resources face depletion, lithium-bearing wastewater from urban mines has become a crucial secondary resource. For highly alkaline (pH 9–12), low-lithium (Li⁺ 0.5–5 g/L), high-sodium (Na/Li mass ratio > 30) wastewater generated from the alkaline leaching-washing of spent lithium-ion batteries in urban mining, a single-component, synergist-free extraction process employing HBL121 in sulfonated kerosene was developed, and its extraction stoichiometry, reaction mechanism, and industrial feasibility were elucidated. Saponification significantly enhanced extraction under moderate alkalinity: the saponified system achieved over 99% extraction efficiency at pH 11.0, whereas the non-saponified system required pH > 13.5 for comparable performance, thereby lowering alkali consumption by 81%. Under optimal conditions (saponification degree 40%, 30% (v/v) HBL121 and 70% (v/v) sulfonated kerosene, organic-to-aqueous phase ratio O/A = 1:1, extraction time 5 min), single-stage extraction efficiency exceeded 99%. A McCabe-Thiele diagram was used to determine the theoretical stage number for lithium stripping, showing that essentially all lithium ions can be stripped via a three-stage countercurrent process. Using 3.0 mol/L H₂SO₄ at an aqueous-to-organic phase ratio of 1:4, the stripping efficiency exceeded 99% from the loaded organic. Slope analysis, FT-IR, and ESI-MS confirmed a coordination mechanism between HBL121 and metal ions, forming a stable anionic bisphosphonate complex [LiNa₂(C₂₈H₄₄O₇P₂)]⁻, whose neutral parent form is HLiNa₂(C₂₈H₄₄O₇P₂). Full article

Gold (Au) is a strategically critical metal whose technological relevance and increasing demand contrast with the long-term decline in primary ore grades. This review discusses gold recovery from primary ores providing the metallurgical and technological baseline for the comparative evaluation of unconventional Au-bearing resources. Emphasis is placed on electronic waste and copper anode slimes as highly valuable secondary raw materials containing gold concentrations comparable to, or exceeding, those in natural deposits. The review examines the origin, chemical and mineralogical characteristics, impurity profiles, and processing routes associated with these materials, including conventional and emerging pyro-, hydro-, and biometallurgical approaches. Material-specific constraints, matrix complexity, recovery efficiency, process limitations, and environmental aspects are discussed in relation to process applicability and technological feasibility. Particular attention is given to the differences between geologically constrained primary ores and heterogeneous secondary Au-bearing materials, whose engineered and continuously evolving compositions influence recovery strategies, limiting the direct application of conventional routes to secondary resources. Finally, the review highlights that primary ores remain the dominant source of global Au production, whereas secondary resources currently represent a complementary component, and outlines key challenges and future directions relevant to the broader utilization of these materials. Full article

Rooibos (Aspalathus linearis) is one of the few endemic South African plants that has achieved economic importance and international acclaim, mostly as a herbal tea. Plant production, limited to a small mountainous region in South Africa, is at risk as commercial rooibos longevity is in decline, mostly due to low stress tolerance. Transcriptome data can serve to identify molecular markers for improved stress response, which would speed up selection and facilitate the establishment of breeding programmes. Previously, rooibos leaf transcriptomes have been sequenced using Illumina, which yields short reads, hampering correct reassembly of full-length transcripts. Here, we established Oxford Nanopore-based, long-read transcriptome analysis for leaf and root samples from rooibos. We report on potential pitfalls in data pre-processing (PolyA tail trimming and rRNA removal), and compare two assemblers (RATTLE and RNA-Bloom2) and two clustering algorithms (VSEARCH and CD-HIT). The best assembly comprising 169,122 transcripts was generated using RNA-Bloom2 with short-read polishing, followed by CD-HIT clustering. Of the 95,054 predicted proteins, only 67% were also present in the Illumina dataset. The remainder comprised substantially shorter, mostly full-length sequences from a wide range of primary and secondary biosynthesis pathways. Functional annotation indicated that this transcriptome represents a high-quality, comprehensive resource for data mining. In the leaf fraction, comparative transcriptomics identified overexpressed rooibos transcripts potentially involved in photosynthesis, photorespiration and carbon fixation. In the roots, overexpressed transcripts encoded enzymes potentially involved in regulation of root growth and secondary metabolite biosynthesis. These transcripts may represent first targets for molecular marker development. Full article

The transition to climate neutrality necessitates a profound transformation of mining systems. In this context, this study focuses on reviewing the role of circular economy models in transforming mining systems. Circular models propose reconfiguring systems into climate-neutral and more resource-efficient configurations. A synthesis of recent literature highlights several circular strategies frequently addressed throughout the mining life cycle. These include waste recovery, secondary resource recovery, water reuse, and the integration of renewable energy. The outcomes of circular approaches have the potential to reduce greenhouse gas emissions and resource consumption. They can also help improve the system’s efficiency through the creation of new economic value streams. Large scale implementation remains constrained because of economic, technological, and governance factors. In light of these findings, the paper recommends an integrated conceptual framework. It ties circular strategies to decarbonization pathways and sustainability outcomes. It does so because the circular economy is not merely a supporting approach but a necessary mechanism to enable the transition to climate-neutral and regenerative mining systems. Full article

The invasive plant Datura stramonium L. possesses strong reproductive capacity and ecological adaptability, showing a tendency to spread rapidly, especially in highly human-disturbed habitats. To explore its resource utilization pathway—turning waste into wealth—and to address toxic metal pollution in strongly human-disturbed areas (such as mining regions), this study evaluates its phytoremediation potential in contaminated soils on the Qinghai–Tibet Plateau. We established a non-planted control and three planting density treatments to compare the removal rates of Pb, Cd, Cr, and As. To our knowledge, this is the first study to assess how planting density influences the multi-metal phytoremediation performance of this invasive species in a high-altitude plateau environment. The results showed that planting significantly increased toxic metal removal rates, with overall efficiency generally improving at higher densities, particularly for Cr. Analysis of bioconcentration and translocation factors revealed distinct element-specific accumulation patterns. Pb and As were primarily enriched and retained in the roots. Interestingly, while Cd exhibited a strong localized tendency to accumulate in the leaves, its overall root-to-shoot translocation remained relatively restricted at the whole-plant level, similar to Cr. Overall, D. stramonium functions primarily through root stabilization for Pb, As, and Cr, alongside partial aboveground accumulation for Cd. However, given its toxic and invasive nature, any practical phytoremediation application requires strict post-harvest biomass management and ecological monitoring to prevent secondary spread. Full article

Coal mining beneath rivers in thick collapsible loess areas involves prominent risks of surface subsidence, riverbed damage, and water inrush, which threaten both mining safety and land–water ecological stability. Taking the Dan River Coal Mine in Shanxi Province, China, as a case area, this study establishes a systematic safety assessment and adaptive remediation framework for longwall mining under complex geological conditions involving collapse columns, dynamic river hydrology, and collapsible loess. A multi-method analytical approach integrating theoretical calculation, 3DEC numerical simulation, and engineering analogy is used to determine the development height of water-conducting fracture zones and the stability of collapse columns. On this basis, a 55 m wide waterproof coal–rock pillar is designed, and the secondary open-off cut is optimized. Surface deformation monitoring shows a maximum surface subsidence of 3.9 m and reveals key movement angles specific to thick collapsible strata. These results support the formulation of adaptive mining control strategies and integrated river protection measures, including composite geomembrane anti-seepage, gabion reinforcement, and overburden grouting for subsidence mitigation. The integrated technical system of pre-mining evaluation, dynamic process control, and post-mining remediation effectively protects river integrity, controls land deformation, and reduces environmental impacts. This study provides a replicable model for safe coal resource extraction, subsidence management, and land–water environmental protection in similar mining areas under rivers and thick collapsible loess conditions. Full article

Mining and metallurgical residues represent one of the largest untapped secondary raw-material resources in Europe; however, their critical raw material (CRM) potential remains insufficiently quantified. This study applies a comprehensive mineralogical, geochemical, and geostatistical framework to evaluate nine distinct waste types from the Cartagena–La Unión Mining District (SE Spain), a historically exploited polymetallic system. A total of 79 samples were analysed using X-ray diffraction, wavelength-dispersive X-ray fluorescence, and advanced multivariate statistical techniques (correlation analysis, principal component analysis and hierarchical clustering) to identify geochemical associations controlling CRM distribution. The results reveal strong geochemical heterogeneity, with systematic enrichment in Co, Ni, Cu, Ga, Nb, and rare-earth proxies. Three dominant geochemical controls were identified: (i) a lithogenic silicate association governing Al–Si–Ti–Nb patterns, (ii) a sulphide-derived metalliferous association characterized by Cu–As–Sb, and (iii) an oxidation–adsorption association responsible for Ga–Y affinity. Several CRM concentrations approach or exceed typical global ore grades for secondary resources, particularly in flotation-derived and oxidation-rich residues. Geostatistical modelling confirms spatially coherent CRM hotspots, with base-metal enrichment linked to sulphide relics and Ga–Nb–Y controlled by Fe–Mn oxyhydroxides. Environmental assessment indicates potential metal mobility under acidic conditions, while also highlighting significant remediation benefits associated with residue reprocessing. Taken together, this study provides a robust and reproducible methodology for CRM assessment in legacy mining wastes and identifies priority residue types within the district with the highest strategic recovery potential. Full article

Chromite beneficiation tailings (CBTs) represent a significant environmental challenge, while simultaneously containing valuable metals that remain largely unrecovered. In this study, a sequential thermochemical–hydrometallurgical route was investigated for selective chromium extraction and the enrichment of platinum group metals (PGMs) from CBTs generated at the Donskoy Mining and Processing Plant. Alkaline sintering with Na₂CO₃ at 1000 °C followed by aqueous leaching enabled the transfer of up to 98%–99% of chromium into solution. The resulting residue was enriched in non-ferrous metals, rare earth elements, and PGMs. Subsequent sulfation roasting and water leaching promoted the dissolution of magnesium, nickel, and rare earth elements, while platinum and palladium remained predominantly in the solid phase, due to their low solubility under the applied conditions. Microstructural analysis using SEM–EPMA revealed that PGMs are selectively concentrated in Ni-bearing micro-inclusions, with local platinum content reaching up to 3.8 wt.% in Ni-rich regions. The proposed sequential processing strategy enables efficient chromium recovery and significant PGM enrichment in the residual phase, demonstrating the potential of CBTs as a secondary resource for integrated metal recovery. Full article

In response to the need to monitor groundwater migration and structural damage to rock strata during tunnel excavation and coal mining, this paper presents a novel electromagnetic detection system that features continuous ground-based transmission and full-waveform underground observation. As the transmitted waveform is crucial for determining the distribution of induced eddy currents and the characteristics of the secondary field response, studying these response characteristics is essential for the system’s practical application. This study selects four typical transmission waveforms—step, triangular, half-sine and trapezoidal—and uses a tetrahedral, three-dimensional grid discretization method to analyze the transient electromagnetic full-wave response patterns of electrical and magnetic sources under different waveform excitations. This elucidates the propagation characteristics of electromagnetic fields in the medium. The research reveals that the waveform type during energization significantly influences the electromagnetic response, with the full-wave response characteristics of electrical and magnetic sources differing significantly in the near-source region and response trends converging in the far-source region. In practical detection, combining the advantages of the three-component responses of the electrical and magnetic sources can effectively improve detection accuracy. The findings of this study provide important theoretical support for optimizing the design of transient electromagnetic detection systems and precisely interpreting detection data. They also lay a theoretical foundation for electromagnetic detection applications in fields such as mineral resource exploration and engineering geological surveys. Full article

Potash is a strategically critical mineral resource essential for ensuring national food security, thereby necessitating the exploration of new deposits to sustain long-term supply. This study systematically evaluates the risk of ground subsidence associated with a “brine extraction–replenishment equilibrium” mining scheme through an integrated framework combining three-dimensional geological modeling and numerical simulation. The research focuses on deep potassium-rich brine resources in the Sanshui Basin, Guangdong Province, China. Geological data from 95 boreholes were processed to construct a high-resolution three-dimensional geological model (61.40 km × 35.20 km × 3.50 km) using Petrel software. Numerical simulations based on poroelastic theory were conducted under multiple extraction scenarios, and the predicted subsidence was assessed against relevant engineering standards for highways and building foundations. The results indicate that: (1) brine extraction from consolidated sandstone represents a fluid displacement process, where the equilibrium scheme induces only minor effective stress redistribution without forming dissolution cavities; (2) global subsidence investigations suggests consolidation primarily affects Quaternary unconsolidated strata, making consolidated sandstone extraction associated with extremely low risk; (3) the maximum subsidence is 5.55 mm and 6.82 mm in the primary and secondary exploration areas, with corresponding surface inclinations of 0.00047‰ and 0.00040‰; (4) unlike solution mining that creates large cavities, deep brine extraction generates no significant inter-stratal pressure differentials. These findings demonstrate that under the extraction–replenishment equilibrium scheme, ground subsidence remains well below the regulatory limits, posing no risk to surface infrastructure. This research provides a scientific foundation for safe development of similar deep brine resources globally. Full article

As secondary educational environments face increasing volatility due to systemic resource constraints and pedagogical uncertainty, understanding the behavioral mechanisms of teacher agency has become paramount. While traditional teacher education has emphasized the execution of standardized curricula, the current era demands a fundamental shift toward adaptive expertise and psychological resilience. This study investigates the processes by which 28 secondary pre-service physical education teachers (PSTs) navigate instructional resource deficits through the lens of adaptive behavior (bricolage) and ecological teacher agency. Utilizing a qualitative case study design, I collected data from two universities in Seoul, South Korea, through reflective journals, revised lesson plans, and micro-teaching video analysis reports over a full 15-week semester. The results identified five coordinates of an adaptive instructional design compass: (1) Facing Constraints, (2) Resource Mining, (3) Contextual Engineering, (4) Simulation, and (5) Reflective Participation. These coordinates represent a transformative behavioral process where PSTs convert environmental deficits into professional assets. The findings reveal distinct adaptation styles based on psychological dispositions: the analytically oriented group (Group A) prioritized structural redesign through digital tools, while the narratively oriented group (Group B) utilized human-centric somatic metaphors and virtual rehearsals to bridge the epistemic void. Crucially, this research suggests that teacher adaptation is not a mere technical adjustment but a dynamic behavioral achievement of agency that ensures the long-term instructional quality of physical education. I propose that teacher education programs should incorporate “Safe Deficit” simulations—carefully calibrated instructional constraints—to trigger adaptive behavior and ensure that future educators can thrive in unpredictable pedagogical contexts without the risk of professional burnout. Full article

Abandoned mining areas provide valuable opportunities to investigate ore-forming processes, supergene mineral transformations, and the geochemical behaviour of metals. In this sense, the old Preguiça mine (Beja, Portugal), exploited for Fe–Zn–Pb, was studied providing new mineralogical and geochemical data aimed at improving the understanding of the secondary mineral assemblages of this deposit. A total of 70 samples collected from three accessible underground levels (first, second and third) and mine waste, complemented by 16 samples from a deeper level (fourth) previously collected, were analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and a portable X-ray fluorescence (pXRF) equipment. Mineralogical phases are dominated by a wide range of secondary oxides, carbonates, arsenates, vanadates, silicates, phosphates and sulphates, but remnants of primary sulphides were also found. The following minerals can be emphasised: goethite, hematite, calcite, dolomite, descloizite, willemite, mimetite, cerussite, smithsonite and fraipontite. The presence of massicot in the Preguiça mine, is described for the first time. Bulk geochemical analyses show high concentrations of Fe, Ca, Zn and Pb, consistent with the observed mineralogy. The presence of vanadium- and arsenic-bearing minerals highlights the occurrence of critical raw materials, supporting the importance of reassessing other abandoned mining areas in the context of sustainable resource management and strategic raw-material planning. Full article

Coal preparation tailings from the K18 seam of the Abayskaya mine were evaluated as a potential secondary source of critical rare earth elements (REEs). The study showed that REEs are predominantly associated with the mineral fraction of coal; therefore, during beneficiation, approximately 70% of their total content is transferred to flotation tailings. The concentrations of valuable elements in the tailings are as follows (g/t): Li—65; Sc—16; Y—17; Yb—2.5; V—135; and Ti—2293. These values significantly exceed the Clarke values and are comparable to those of some low-grade primary ores, indicating the potential of coal preparation wastes as a technogenic raw material for critical elements. To extract REEs from the resistant aluminosilicate matrix, a fluorine–ammonium sulfate thermochemical activation method was proposed. Using a probabilistic–deterministic experimental design approach, a mathematical model of the process was developed and optimal parameters were determined (400 °C, 120 min, (NH₄)₂SO₄ consumption—140% relative to Al, NH₄HF₂ consumption—110% relative to Si), providing a feed liberation degree (by Al extraction) of up to 94%. Under optimal conditions, high leaching efficiencies of key elements were achieved: Sc (95%), Y (100%), Yb (100%), and Li (100%). The results demonstrate the significant potential of coal preparation tailings as a secondary resource of rare earth elements and confirm the efficiency of fluorine–ammonium sulfate technology for processing this type of technogenic waste. Full article