Search Results (839)

Small-scale artisanal mine production processes are characterized by significant environmental and human health impacts, especially in countries with ineffective economic resources and policies. This study accurately quantifies the impacts of artisanal gold production processes, identifying the dominating hotspots in a holistic perspective. The life cycle assessment (LCA) methodology was applied to perform an environmental sustainability appraisal for Doré and Cyanidation Gold (CyG) extraction from Mina Nueva, a small-scale artisanal mine managed by the local population, located in Asociación Campesina del Valle del río Cimitarra, near the city of Segovia in the department of Antioquia in Colombia. The obtained single-score LCA results showed a total damage of 4.99 × 10⁰² Pt, of which 55.2% was associated with the cyanidation process, 34.4% with the whole-ore amalgamation phase, and 10.4% with mine construction. A sensitivity analysis was also performed to study the potential effects of particulate emissions generated by the mine construction phase. Full article

The removal of copper–cyanide complexes from cyanide gold leaching tail water poses a significant challenge, as they are difficult to eliminate and risk causing secondary pollution. This study developed a synergistic flocculation–flotation process using the bio-collector sodium cocoyl glycinate (SCG) and the coagulant polyferric sulfate (PFS) for purification. Simulated wastewater, prepared based on actual gold mine effluent, was treated under optimized conditions of reagent dosage, a solution pH of 6–10, and a flotation time of 1–5 min, achieving high removal efficiencies of 96.48% for copper and 94.68% for total cyanide. Mechanistic studies via FT-IR, Zeta potential, and XPS revealed that Fe³⁺ from PFS formed Fe-CN complexes with both free and copper-complexed cyanide. Simultaneously, copper ions coordinated with SCG to generate a hydrophobic Fe-CN-Cu-SCG ternary complex, which was subsequently removed by adsorption onto air bubbles via the hydrophobic chains of SCG. This work provides a novel, efficient, and mechanistically clear strategy for the advanced treatment of cyanide-containing tailing water with a gold content of 0.021 mg/L. Full article

This study evaluated the geochemical contamination and ecological risk of metal(oid)s (As, Cd, Cr, Cu, Pb, Hg, and Zn) in sediments from four sites within a section of the Madre de Dios River, Peru—an area affected by artisanal alluvial gold mining and with limited prior research that considers its local geochemical complexity. Sediment samples were collected between 2013 and 2020, spanning seven river flood seasons and four low river flow seasons. Background values were estimated using ProUCL 5.2, considering local climatic and geological conditions. Environmental quality indices revealed that sediments in the studied river section were mainly contaminated and exhibited high ecological risk due to Hg, used in gold amalgamation, which showed peak values in 2013 and subsequently declined to moderate levels. Cd exhibited contamination and ecological risk until 2016, with non-detectable values thereafter, while As, Cu, Cr, Pb, and Zn showed low environmental alteration. Factor analysis and principal component analysis indicated a natural origin for Cu, Cr, Pb, and Zn, whereas Hg showed an anthropogenic source linked to mining. Elevated concentrations of Hg, Cr, and Zn during the river flood season highlight the influence of hydrological dynamics on contaminant mobilization within these sites of the river section. Full article

Balancing high fluidity and stability is a critical challenge in deep-shaft cemented paste backfill (CPB) with high-concentration tailings. This study investigates the synergistic regulation mechanism of a combined admixture system comprising hydroxypropyl methylcellulose (HPMC) thickener and polycarboxylate (PCE) or Melamine-Formaldehyde Resin (MFR) superplasticizers on CPB rheology, mechanical strength, and microstructure. Results indicate that HPMC significantly enhanced anti-segregation performance via intermolecular bridging, substantially increasing yield stress and plastic viscosity. Upon PCE introduction, the steric hindrance provided by its side chains effectively disrupted HPMC-induced flocs and released entrapped water. Consequently, yield stress and plastic viscosity were reduced by up to 22.1% and 64.3%, respectively, with PCE exhibiting markedly superior viscosity-reducing efficiency compared to MFR. Mechanical testing revealed that PCE co-addition did not compromise early-age strength but enhanced 3, 7, and 28-day unconfined compressive strength (UCS) by refining pore structures and promoting the uniform distribution of hydration products. Microstructural analysis unveiled a competitive adsorption mechanism: preferential PCE adsorption dispersed particle agglomerates, while non-adsorbed HPMC formed a viscoelastic network within the pore solution, constructing a stable “dispersion-suspension” microstructure. This work provides a theoretical basis for optimizing high-performance backfill formulations. Full article

The inherent complexity of the decision-making process in early-stage mining projects demands high-risk investments, often based on limited and low-confidence data. The geometallurgical approach offers an opportunity to mitigate uncertainties through the development of mathematical models to predict key process variables, such as recovery and specific energy. This research quantifies the economic and technical impact of incrementally increasing the number of variables in a geometallurgical model of a copper-gold-silver polymetallic deposit during the Pre-Feasibility Study (PFS) phase. Regression models were developed to correlate grades (copper, gold, and silver) and metallurgical variables (recovery and specific energy). The models were applied to eight geometallurgical block models, and technical and economic results were generated using Direct Block Sequencing (DBS). Across all scenarios, increased model complexity had a modest effect on production metrics but caused notable variation in Net Present Value (NPV), reaching a 6.92% difference between scenarios. Thus, adding more geometallurgical variables is justified not by higher production tonnage but by the potential to enhance and stabilize NPV through improved sequencing based on key value drivers (costs, recoveries and processing time). These findings highlight the value of early geometallurgical modeling, even with limited data, for producing a more integrated and improved economic assessment. Full article

To address clock drift arising from the absence of GPS synchronization during ocean-bottom seismic observations, we propose a time-offset correction and quality-control scheme that uses the correlation of P-wave empirical Green’s functions (EGFs) as the metric, and we demonstrate its efficacy in mitigating cross-correlation asymmetry caused by azimuthal noise in shallow-water environments. The method unifies the time delays of the four components into a single objective function, estimates per-node offsets via sparse weighted least squares with component-specific weights, applies spatial second-difference smoothing to suppress high-frequency oscillations, and performs spatiotemporally constrained regularized iterative optimization initialized by the previous day’s inversion to achieve a robust solution. Tests on a real four-component ocean-bottom node (4C-OBN) hydrocarbon exploration dataset show that, after conventional linear clock-drift correction of the OBN system, the proposed method can effectively detect millisecond-scale time jumps on individual nodes; compared with traditional noise cross-correlation time-shift calibration based on surface-wave symmetry, our four-component fusion approach achieves superior robustness and accuracy. The results demonstrate a marked increase in the coherence of the four-component cross-correlations after correction, providing a reliable temporal reference for subsequent multicomponent seismic processing and quality control. Full article

Screening is a critical link in the separation of gold ores. However, issues such as the agglomeration of material masses and screen aperture blinding often lead to low screening precision and poor desliming performance, severely impacting the efficiency of subsequent crushing processes. To address these challenges, this paper proposes a rigid–flexible coupled screening method for viscous and moist gold ores. The time-frequency response characteristics of the screen surface motion were investigated, the influence of processing capacity and moisture content on screening performance was analyzed, and an industrial performance evaluation of the rigid–flexible coupled screen surface was conducted. Laboratory and industrial test results demonstrate that the rigid–flexible coupled screen surface exhibits a periodic, non-regular waveform with a maximum peak vibration intensity of 14.79 g. Screening efficiency is synergistically inhibited by moisture content and processing capacity. When the ore moisture content is below 3% and the processing capacity ranges from 15 to 22.5 t/(h·m²), the screening efficiency can exceed 85%. Compared with conventional screen surfaces, the implementation of the rigid–flexible coupled screen surface achieved a desliming efficiency of 91%, a maximum processing capacity in the crushing stage of 380 tons per hour, a nearly 12% improvement in the screening efficiency of the closed-circuit checking process for crushed products, and an approximately 8% reduction in the circulating load ratio of the crushing circuit. These enhancements collectively ensure the stable operation of both the screening and crushing processes. Full article

This article presents a comprehensive analysis of the primary electrical power distribution system in hybrid-electric aircraft, with particular emphasis on its environmental performance assessed through Life Cycle Assessment (LCA). High-resolution Life Cycle Inventory (LCI) data were developed in collaboration with industry partners and refined to reflect current production standards. The results indicate that printed circuit boards (PCBs), magnets, precious metals (gold and silver), and copper are the primary contributors to environmental impact, with PCBs alone accounting for over 50% of material-related emissions. Although precious metals constitute only 0.014% of the product’s mass, they account for nearly 9% of total emissions due to the energy-intensive nature of their mining and refining processes. Additionally, manufacturing stages involving thermal treatments—such as surface coating of iron cores at 850 °C for 14 h—significantly increase energy consumption and associated emissions. The study concludes with recommendations for reducing the carbon footprint of future aircraft power systems through improved material efficiency, process optimization, and supply chain sustainability. Full article

The progressive depletion of high-grade ore bodies has shifted attention toward the exploitation of lower-grade deposits as viable sources of value. In recent years, there has been growing emphasis on mining and processing methods that incorporate sustainability by addressing both environmental and socio-economic considerations. To maximize resource recovery, integrated strategies that combine exploration, grade control drilling, mine planning, and processing are essential. Within this framework, particle sorting has emerged as an effective coarse separation method that can upgrade low-grade feed prior to the more energy-demanding milling and subsequent processing stages. Incorporating screening before particle sorting not only assists in identifying the distribution of metals but also determines the most suitable particle size ranges for sorting performance. This study reports on the applicability of sensor-based sorting technologies to low-grade gold and nickel ores from Australia, with a focus on grade deportment by particle size. The results demonstrate that substantial upgrading of low-grade ores is possible, achieving 70%–80% metal recovery within approximately 30%–40% of the original mass through the use of induction and XRT sensors. Overall, the findings indicate that both induction and XRT sorting methods are broadly effective across ore types, offering enhanced upgrading capability and improved processing efficiency. Full article

The iron-oxide-copper-gold (IOCG) skarns of the Tatatila-Las Minas mining district in central Mexico represent a structurally-controlled, exhumed fossil geothermal system located in the eastern sector of the Trans-Mexican Volcanic Belt (TMVB). The district was historically exploited for gold and copper mineralization. The emplacement of the ore bodies was controlled by regional Neogene–Quaternary NE- and NW-striking fault systems formed during the extensional evolution of the TMVB. These faults acted as conduits for high-temperature hydrothermal fluids circulating during the cooling of the Neogene magmatic intrusions. By integrating detailed field study with available exploration borehole data, the spatial distribution of the skarn bodies was reconstructed. Three main emplacement geometries were identified: (a) at contacts between magmatic bodies and host rocks, (b) as lenticular or irregular bodies parallel to the host rock foliation, and (c) at the intersections of near-orthogonal faults. Although structural controls on skarn formation represent a key factor in ore emplacement, their analysis remains scarcely explored. This paper therefore contributes to filling this gap by providing a detailed characterization of the structural framework governing IOCG skarn development at Tatatila–Las Minas. The results improve understanding of IOCG systems formation and provide predictive criteria for mineral exploration in similar geological settings, potentially reducing exploration and mining risks. Full article

This study investigates the settlement characteristics of overlying strata in backfilled stopes at the Sanshandao Gold Mine, focusing on the compaction behavior of backfill materials. Integrating laboratory tests, numerical modeling, and field monitoring, we analyzed the particle size distribution and fractal dimensions of tailings (2.1525) and C material (2.1994), with tailings showing better gradation. Systematic compaction tests examined the effects of mix ratio, water content, and curing time. Results indicate that compression follows a viscous sliding model with exponential curves, progressing through three stages—pore compaction, structural deformation, and elastic/plastic deformation—with energy dissipation ratios of 1:5:18. Water content was the most influential factor, with optimal compaction occurring at 5~8%. Coupled Midas-Flac3D simulations estimated a theoretical compaction rate of 0~2% in filled stopes, excluding seepage and equipment effects. Field monitoring at the −480 m level revealed non-uniform settlement, with maximum subsidence of 63.75 mm above stopes and initial settlement rates of 12~20 mm/month. At the −520 m mining level, the backfill compaction rate reached 0.31%, with minor future increases expected. These findings offer valuable guidance for backfill mixture design and strata control in mining engineering. Full article

The preferential concentration of metals into finer size fractions (<19 mm) during breakage can be exploited for early rejection of low-grade material, reducing non-ore processing and improving energy and water efficiency. The Cooperative Research Centre for Optimising Resource Extraction (CRC ORE) established a testing regime and developed the Response Ranking (RR) factor to compare fractionation behavior across deposits. RR values range from 200 to negative, with higher values indicating breakage patterns favorable for ore liberation. This study evaluates geological parameters controlling rock breakage in the Gramalote and Telfer West Dome deposits, both intrusion-related gold systems. For this purpose, macroscopic description of drill core was carried out using the Anaconda methodology, along with uncrushed run-of-mine (ROM) samples. In addition, petrophysical datasets including hardness, magnetic susceptibility, hyperspectral data, geochemistry, and calculated mineralogy were used. These datasets were systematically compared with RR values to investigate the relationship between geological attributes and grade-by-size fractionation behavior. Geological description provides a practical basis to identify early separation opportunities and model optimization potential through grade-by-size fractionation. Full article

While artisanal gold mining (AGM) has been credited as a sector that sustains many households in Zimbabwe, it has at the same time been criticized as the chief driver of ecological degradation and social vulnerability. This study qualitatively examines the environmental and socioeconomic impacts of AGM by conducting in-depth interviews with miners, residents, and policymakers across six central mining districts. The study findings indicate that the use of mercury has resulted in severe contamination of water bodies, while clearing land to pave the way for mining has led to severe deforestation, loss of biodiversity, and declining agricultural productivity due to the loss of fertile soils. It was also found that most AGMs were unregulated, and their unregulated operations have intensified health risks, social inequality, and land-use conflicts with the local community. This study provides an insight into how dependence on AGM has perpetuated a cycle of ecological degradation and poverty among many Zimbabweans. The study, therefore, attempts to combine community narratives with policy analysis, thereby proposing a framework for sustainable AGM in Zimbabwe. This involves advocating for the use of environmentally friendly technologies and promoting participatory environmental governance among all key stakeholders. The study contributes to achieving a balance between economic benefits and environmental management by advancing the discourse on sustainable development and community resilience in resource-dependent economies. Full article

Gold mining has played a central role in shaping Peruvian society from pre-Inca civilizations to the present. However, existing literature offers fragmented perspectives, often focusing on isolated themes such as metallurgy, colonial mercury use, or environmental degradation, without integrating these across time and territory. This review addresses that gap by offering a place-based synthesis that combines archaeological, historical, legal, environmental, and comparative insights. Drawing on both Spanish-language sources and international literature, the paper reconstructs Peru’s gold mining trajectory through five historical phases—pre-Inca, Inca, colonial, republican, and contemporary—highlighting continuities and ruptures in governance, labor systems, and environmental impacts. The analysis reveals persistent challenges in Peru’s gold sector, including informality, mercury pollution, and weak institutional capacity. Compared to other mining economies such as Chile, Ghana, and South Africa, Peru exhibits greater fragmentation and limited integration of mining into national development strategies. The review also explores the role of gold in the global energy transition, emphasizing its relevance in clean technologies and green finance, and identifies policy gaps that hinder Peru’s alignment with sustainability goals. By bridging linguistic and disciplinary divides, this synthesis contributes to a more inclusive historiography of extractive industries and underscores the need for interdisciplinary approaches to mining governance. Ultimately, the paper calls for a reimagining of Peru’s gold sector, one that prioritizes environmental justice, social equity, and long-term resilience. Full article