Search Results (180)

The increasing demand for critical raw materials such as copper and cobalt highlights the need for efficient beneficiation of low-grade ores. This study investigates a copper–cobalt sulfide ore (0.99% Cu, 0.028% Co) using froth flotation to produce high-grade concentrates. Various types of surfactants are applied in different ways, each serving an essential function such as acting as collectors, frothers, froth stabilizers, depressants, activators, pH modifiers, and more. A series of flotation tests employing different collectors (SIPX, PBX, AERO, DF 507B) and process conditions was conducted to optimize recovery and selectivity. Methyl isobutyl carbinol (MIBC) was consistently used as the foaming agent, and 700 g/L was used as the slurry density at 25 °C. Dosages of 30 and 100 g/t¹ were used in all tests. Notably, adjusting the pH to ~4 using HCl significantly improved cobalt concentrate separation. The optimized flotation conditions yielded concentrates with over 15% Cu and metal recoveries exceeding 80%. Mineralogical characterization confirmed the selective enrichment of target metals in the concentrate. The results demonstrate the potential of this beneficiation approach to contribute to the European Union’s supply of critical raw materials. Full article

Global resource consumption continues to grow each year, exerting increasing pressure on their availability. This trend could lead to a shortage of raw materials in the coming years. Aware of the risks associated with this situation, the European Union has implemented policies and strategies aimed at diversifying its supply sources, including waste recycling. In this context, the present study was conducted with the objective of developing innovative processes to concentrate valuable metals present in the non-recovered fractions of waste electrical and electronic equipment (WEEE). Three types of samples were studied: washing table residues (WTRs), printed circuit boards (PCBs), and powders from cathode-ray tube screens (CRT powders). Several separation techniques, based on the physical properties of the elements, were implemented, including electrostatic separation, magnetic separation, and density and gravity-based separations. The results obtained are promising. For WTRs and PCBs, the recovery rates of targeted metals (Cu, Al, Pb, Zn, Sn) reached approximately 91% and 80%, respectively. In addition to these metals, other valuable metals, present in significant quantities, deserve further exploration. Regarding CRT powders, the performances are also encouraging, with recovery rates of 54.7% for zinc, 57.1% for yttrium, and approximately 71% for europium. Although these results are satisfactory, optimizations are possible to maximize the recovery of these critical elements. The techniques implemented have demonstrated their effectiveness in concentrating target metals in the treated fractions. These results confirm that recycling constitutes a viable alternative to address resource shortages and secure part of the supplies needed for the European Union’s industry. Full article

The growing consumption of oil and gas resources and the increasing difficulty of extraction have created major challenges for traditional manufacturing and maintenance, particularly in the timely supply of critical components, customized production, and complex structure fabrication. Additive manufacturing (AM) technology, with its high design freedom, precision, and rapid prototyping, provides new approaches to address these issues. However, systematic reviews of related efforts are scarce. This paper reviews the applications and progress of metal and non-metal AM technologies in oil and gas extraction and gathering engineering, focusing on the just-in-time (JIT) manufacturing of failed components, the manufacturing and repair of specialized equipment and tools for oil and gas extraction and gathering, and artificial core and reservoir geological modeling fabrication. AM applications in this field remain exploratory and face challenges with regard to their standards, supply chains, materials, and processes. Future research should emphasize developing materials and processes for extreme conditions, optimizing process parameters, establishing standards and traceability systems, and integrating AM with digital design and reverse engineering to support efficient, safe, and sustainable industry development. This work aims to provide a reference for advancing AM research and engineering applications in the oil and gas sector. Full article

Soil aggregates play critical roles in regulating the behavior of heavy metal in soils. To understand the distribution of cadmium (Cd) in aggregates of different soil types, as well as their roles in regulating the Cd bioavailability of bulk soils, four major arable soils, including acidic, neutral, and calcareous purple soils and calcareous yellow soil (APS, NPS, CPS, and CYS), were sampled from Chongqing, China, for aggregate separation and determination of the total Cd(T-Cd) distribution, fractionation, and extractability in various-sized aggregates. A pot experiment with ryegrass (Lolium perenne L.) was conducted to evaluate the Cd bioavailability in bulk soils as influenced by aggregates. The results show that the composition of soil aggregates varies a lot among soils: lower soil pH tends to increase the proportion of macroaggregates while decreasing that of smaller aggregates. The Cd distribution, HCl-extractability, and active fraction (AF, T-Cd/HCl-Cd) in aggregates are all soil type-dependent, with pH and particle size being the main determining factors; the distribution pattern of Cd concentrated in smaller aggregates is only found for CPS and CYS (pH > 7.5) upon exogenous Cd addition, though the finest aggregates (silt–clay, <0.053 mm) consistently exhibited the highest Cd enrichment for all tested soils. The Cd extractability and AF values in all aggregates show a sequence of APS > NPS > CPS > CYS, indicating the fundamental influence of soil pH on Cd availability. Higher AF values over bulk soils, either in silt–clay aggregates or in microaggregates (0.053–0.25 mm), whereas lower AF in macroaggregates (1–2 mm) are found for APS and NPS, which correspond to the relative portions of Ex-Cd and Fe/Mn oxide-bound Cd (Fe/Mn-Cd) in these aggregates. In contrast, less variation of AF values among aggregates is observed for CPS and CYS and for APS/NPS upon Cd addition. Pot experiments demonstrated strong positive correlations between ryegrass Cd uptake and HCl-Cd in silt–clay aggregates and T-Cd in microaggregates, while a negative correlation was observed with T-Cd in macroaggregates. These findings supply new insight into the mechanisms of aggregates in controlling Cd bioavailability in bulk soils and shed light on the development of new strategies for remediating Cd-polluted soils. Full article

In a dynamic global market, platinum-group metals (PGMs), particularly palladium, are in high demand across various industries due to their unique properties. Palladium plays a crucial role in environmentally friendly technologies, such as catalytic converters, which mitigate harmful automotive emissions. Additionally, it is essential for clean energy production, particularly in hydrogen generation, which makes palladium a critical resource for building a sustainable and secure supply chain. This study evaluates the prospects of the palladium market through strategic analysis, focusing on the Russian mining and metals company PJSC MMC Norilsk Nickel. The research employs strategic and industry analysis methods to examine palladium production, market dynamics, and technological advancements, as well as emerging applications in the context of a green economy. The article analyzes the economics of palladium production, including price volatility driven by stringent environmental regulations and the rising adoption of electric vehicles. The palladium market faces challenges such as a constrained resource base, supply disruptions due to sanctions, price instability, and growing demand from key sectors, particularly the automotive industry. Nevertheless, innovation-driven trends offer promising opportunities for market growth, aligning with sustainable development principles and the transition toward a green, low-carbon economy in both established and emerging markets. As a key scientific contribution, this study proposes a modified methodological approach to industry analysis, enabling the assessment of a mining and metals company’s competitive sustainability in the palladium market over the medium and long term. Furthermore, the research models the life cycle of palladium as a commodity, considering evolving market trends and the rapid development of new industries within the green economy. Full article

With the enhancement of thermodynamic cycle parameters and heat dissipation constraints in aero-engines, effective thermal management has become a critical challenge to ensure safe and stable engine operation. This study developed a transient temperature evaluation model applicable to the entire flight envelope, considering fluid–solid coupling heat transfer on both the main flow path and fuel systems. Firstly, the impact of heat transfer on the acceleration and deceleration performance of a low-bypass-ratio turbofan engine was analyzed. The results indicate that, compared to the conventional adiabatic model, the improved model predicts metal components absorb 4.5% of the total combustor energy during cold-state acceleration, leading to a maximum reduction of 1.42 kN in net thrust and an increase in specific fuel consumption by 1.18 g/(kN·s). Subsequently, a systematic evaluation of engine thermal management performance throughout the complete flight mission was conducted, revealing the limitations of the existing thermal management design and proposing targeted optimization strategies, including employing Cooled Cooling Air technology to improve high-pressure turbine blade cooling efficiency, dynamically adjusting low-pressure turbine bleed air to minimize unnecessary losses, optimizing fuel heat sink utilization for enhanced cooling performance, and replacing mechanical pumps with motor pumps for precise fuel supply control. Full article

The tungsten deposits in Mongolia have the potential to be exploited as an alternative source to alleviate the risk due to the monopolization in the global production of such a critical metal. However, it is challenging to develop an efficient mineral processing method that can complement the supply based on the currently available energy resources in Mongolia. Therefore, the present study investigated the range of energy required for the beneficiation of tungsten ores, including theoretical assumptions and practical evaluation for two processes in Mongolia. The range of energy consumption was 0.12 to 2.21 kWh/t for crushing and 0.29 to 4.62 kWh/t for grinding regarding the range of Kick’s constant 0.2–0.6 kWh/t and Bond work index 7–17 kWh/t, respectively. The most dominant impact factor in the comminution was the product size. The evaluation of 18 different comminution–flotation circuits indicated a range of required energy from 362 kWh to 8298 kWh. The maximum values of energy consumption for mineral processing of Erdene-soum and Khovd Aimag tungsten ore were 6280 and 6355 kWh. An estimation regarding the energy demand (6355 kWh) and supply energy for the process of Khovd Aimag ore was conducted to propose a suitable system of renewable energy resources using the power pinch analysis method. Full article

The High Andean region of Peru, characterized by a complex orography, has unique and highly biodiverse ecosystems. This region has several headwater basins that play a critical role in the hydrological cycle, providing diverse ecosystem services essential to sustain biodiversity and supply water to human communities. Despite the importance of this region, it faces significant human intervention, particularly mining activities, which affect basin headwaters and jeopardize water security. This study aimed to calibrate the Biological Monitoring Working Party (BMWP) index to evaluate water quality in High Andean rivers in Peru affected by mining activities, using aquatic macroinvertebrates as bioindicators. We used a 15-year dataset (2008 to 2023) from three headwater basins in the High Andean region; this dataset included physicochemical water quality parameters, trace metals, and aquatic macroinvertebrates. The BMWP was calibrated for the High Andean region of Peru with this dataset (BMWP/PeIAZIM); afterward, it was validated to assess water quality in an area influenced by mining activities in this region. The results allowed us to differentiate between aquatic macroinvertebrate families tolerant to mining pollution and highly sensitive families. The sites heavily affected by mining activity returned very low BMWP/PeIAZIM scores; sites with no mining impact had the highest scores. These findings indicate that the calibrated index can be used for water resource management in the High Andean region, contributing to the conservation of its ecosystems. Full article

This article examines urban mining in Brazil, highlighting its unique context compared to other regions. While European Union focuses on critical metal supply and advanced Waste Electrical and Electronic Equipment (WEEE) legislation and circular economy, Brazil’s urban mining is primarily driven by waste management and social inclusion. The current investigation was underpinned by the PRISMA extension for Scoping Reviews (PRISMA-ScR framework), using targeted searches on the Web of Science platform for technological processes and the Brazilian scenario, complemented by an analysis of legislative evolution and a Critical Discourse Analysis of national policies. The results indicate that, despite advanced legislation, significant gaps exist between discourse and practice, highlighting the need for technological appropriation, specific public policies that incentivize reverse logistics and the integration of the informal sector, and overcoming infrastructural challenges. It concludes that Brazil has a unique opportunity to develop an urban mining model that pioneeringly integrates environmental sustainability, technological innovation, and social inclusion, demanding coordinated efforts to overcome existing barriers. Full article

Lithium and its compounds have become crucial energy metals and industrial necessities. Driven by technological advancements and expanding applications in energy storage and portable electronics, ensuring sustainable lithium supply chains is highly important. Thus, the development of efficient extraction methods from salt-lake brines, particularly those with high Mg²⁺/Li⁺ ratios, has become a priority. Nanofiltration (NF) separation technology has recently emerged as a key process for selective lithium recovery, presenting remarkable advantages over conventional methods. This review systematically assesses the relationships between the polymeric structure and sieving performance of NF membranes for lithium extraction. This research emphasizes the influence of the membrane architecture on ionic selectivity and permeability. Advanced modification strategies for positively charged NF membranes are meticulously analyzed. These strategies include surface functionalization, copolymer design, and hybrid nanocomposite engineering, all of which are aimed at increasing the Mg²⁺/Li⁺ separation efficiency. Moreover, the review delves into innovative membrane module configurations and coupling processes (such as the integration of NF-electrodialysis) to satisfy the requirements of industrial scalability. Finally, the critical challenges and future research directions are highlighted. Our focus lies on cost-effective membrane fabrication, the optimization of long-term stability, and system-level process intensification. This comprehensive analysis not only provides an in-depth mechanistic understanding of high-selectivity lithium extraction from complex brines but also stimulates the rational design of next-generation membranes with precisely tailored ion-transport properties. Full article

The international seabed area (“the Area”) harbors abundant metal mineral resources that are critical to address global metal supply–demand and sustainable development. However, exploitation of mineral resources in the Area faces complex risks spanning politics, economy, technology, science, environment, society, industry, and law. No commercial-scale deep-sea mining operations have been conducted to date. Systematic risk identification and prioritization can inform strategic planning for stakeholders. This study employs literature analysis and an 80-expert questionnaire to identify key risk factors affecting mineral exploitation in the Area. Using the Analytic Hierarchy Process (AHP), we quantitatively assess the relative importance and weightings of these risks. Our results indicate that Level 1 risk groups prioritize (1) policy and public opinion risk, (2) extended continental shelf (ECS) delineation risk, (3) high sea marine protected areas (HSMPAs) establishment risk, and (4) mining area economic value risk. The five most critical Level 2 risk factors are (i) policy changes in contractor states, (ii) ECS-mining area boundary conflicts, (iii) environmental provisions in exploitation regulations at the international seabed (ER), (iv) ER implementation delays, and (v) mineral resource uncertainty. These findings provide actionable insights for contractors, policymakers, and stakeholders to optimize decision making in deep-sea mining projects. Full article

Critical raw materials are economically and strategically important for industry both in the short and long term. However, their supply is at high risk due to limited domestic deposits and reliance on imports. As demand for these materials grows, alternative sources must be explored. This study investigates the recovery of critical raw materials from waste, focusing on incineration residues, industrial byproducts, and electronic waste. The research analyzes various waste streams, including municipal solid waste incineration bottom ash and fly ash, as well as electronic and industrial waste, to determine their potential as secondary sources of critical materials. Key elements targeted for recovery include rare earth elements (REEs), antimony, vanadium, cobalt, and other strategic metals. The study evaluates the effectiveness of hydrometallurgical, pyrometallurgical, bioleaching, and electrochemical techniques for their extraction. Findings indicate that bottom ash contains 1–3% ferrous metals and up to 0.4% non-ferrous metals, including rare earth elements, while fly ash has substantial quantities of heavy metals suitable for recovery. The study highlights that large-scale recovery of critical raw materials from waste could reduce reliance on primary sources, support the circular economy, and enhance supply chain resilience in the context of energy transition. By providing a comprehensive assessment of recovery technologies and their economic and environmental implications, this study underscores the importance of waste as a valuable resource for critical material supply. The findings contribute to policy discussions on sustainable resource management and the reduction of geopolitical risks associated with raw material dependency. Full article

Irrigation water quality is of critical importance for optimum crop yield of economically important field crops in the Kahramanmaraş plains. A preliminary ecotoxicological assessment is necessary before large-scale irrigation. Therefore, this study aims to evaluate the quality of irrigation water supplied from different water sources (Karasu, Erkenez, and Oklu streams on the Aksu River and Sır Dam) and the effects on the seed germination and early seedling growth of different field crops (wheat, alfalfa, ryegrass, and maize) irrigated with this water. For this, in order to evaluate the effects on seed germination and early growth parameters of forage crop seedlings, a Petri dish germination test was carried out with four replications using a completely randomized design (CRD). Before the germination assay, heavy metal concentrations including copper (Cu), iron (Fe), lead (Pb), chromium (Cr), arsenic (As), nickel (Ni), and cadmium (Cd) were analyzed in water samples obtained from different water sources. In all water samples used for the experiment, Cu concentrations exceeded the acceptable limit of 0.2 mg L⁻¹. The Cu levels found were 0.98 mg L⁻¹ in Karasu (KC), 1.627 mg L⁻¹ in Oklu (OC), 0.945 mg L⁻¹ in Erkenez (EC), and 1.218 mg L⁻¹ in Sır Dam (SD) waters. Additionally, Fe exceeded the limit only in KC, while Cd surpassed the permissible levels in EC and SD water samples. Seeds exposed to different water treatments were germinated in a climate chamber at 20 ± 1 °C. Over two weeks, daily germination and seedling growth parameters were measured. The results indicated that higher heavy metal concentrations in irrigation water led to a decline in seed germination rates and adversely impacted early seedling growth. Notably, water from Karasu Creek exhibited the most significant negative impact on all germination and growth parameters in the tested crops, especially due to Cu and Fe metal toxicity. Additionally, ryegrass seeds were most affected by these irrigation waters. This study highlights the importance of using uncontaminated quality irrigation water for optimal crop production by quantifying its impact, such as the percentage of decrease in germination or seedling growth. Full article

Metal hydride-based hydrogen storage (MHHS) has been used for several purposes, including mobile and stationary applications. In general, the overall MHHS performance for both applications depends on three main factors, which are the appropriate selection of metal hydride material uses, design configurations of the MHHS based on the heat exchanger, and overall operating conditions. However, there are different specific requirements for the two applications. The weight of the overall MHHS is the key requirement for mobile applications, while hydrogen storage capacity is the key requirement for stationary applications. Based on these requirements, several techniques have been recently used to enhance MHHS performance by mostly considering the faster hydrogen absorption/desorption reaction. Considering metal hydride (MH) materials, their low thermal conductivity significantly impacts the hydrogen absorption/desorption reaction. For this purpose, a comprehensive understanding of these three main factors and the hydrogen absorption/desorption reaction is critical and it should be up to date to obtain the suitable MHHS performance for all related applications. Therefore, this article reviews the key techniques, which have recently been applied for the enhancement of MHHS performance. In the review, it is demonstrated that the design and layout of the heat exchanger greatly affect the performance of the internal heat exchanger. The initial temperature of the heat transfer fluid and hydrogen supply pressure are the main parameters to increase the hydrogen sorption rate and specific heating power. The higher supply pressure results in the improvement in specific heating power. For the metal hydride material selection under the consideration of mobile applications and stationary applications, it is important to strike trade-offs between hydrogen storage capacity, weight, material cost, and effective thermal conductivity. Full article

Copper is a critical metal required for green energy technologies such as wind turbines and solar cells. However, copper supply is limited by copper recovery from primary copper sulphides (e.g., chalcopyrite-CuFeS₂) due to passivating reaction products. Therefore, this study examined surface ‘passivation’ of primary copper sulphide minerals undergoing coupled dissolution with reprecipitation (CDR) reactions and the associated mineral surface changes in acidic and chloride-rich lixiviants (FeCl₃-only, AlCl₃-rich, NaCl-rich, and CaCl₂-rich lixiviants). Acidic FeCl₃-only, NaCl-rich, and CaCl₂-rich lixiviants resulted in only bornite dissolution and the formation of a residual Cu-S phase and Fe-SO₄ phase on the chalcopyrite surface. In contrast, leaching with the AlCl₃-rich lixiviant resulted in both chalcopyrite and bornite dissolution with limited hydrolysis of Fe³⁺ to Fe-hydroxy sulphates and minimal Fe³⁺ flux inhibition to the copper sulphide minerals surface due to the ion exchange mechanism between Al³⁺ and Fe³⁺. Further, there was preferential formation of an Al-SO₄ phase at consistently high Eh and acidity, thereby a high availability of Fe³⁺ in solution for enhanced copper dissolution from both bornite and chalcopyrite. These findings could serve as a reference for coupled dissolution with reprecipitation reactions during copper sulphide leaching, offering a pathway to more efficient and sustainable copper extraction from low-grade ores. Full article