Metal Mining Research Articles

Investigation of the Application of Complex Function Theory in Underground Mine Design: A Case Study

This study, with the engineering background of the design of a stope involving a sublevel mining method in a certain underground metal mine, explored the application of stress-solving methods based on the complex variable function theory in actual engineering. Three mathematical calculation models based on the functions of a complex variable were established. Through triangle interpolation, mapping functions of a plane with a roadway section and a plane with the stope section were determined. An improved Schwarz alternating method was adopted to study the stability of the roadway and the influence of an adjacent roadway from the perspective of the stress field. In addition, in light of the distribution characteristics of a gangue in the stope, the design parameters of a pillar were optimized, with the pillar’s optimal dimensions determined. The results showed that when the magnitudes of two far-field principal stresses in the rock mass are relatively close, the distribution of the surrounding rock stress around the roadway is more uniform, and tensile stress is less likely to occur. The excavation of a neighboring roadway exacerbates to some extent the side stress of the other roadway, especially the compressive stress concentration on the side closer to the neighboring roadway. However, when the distance between the two roadways is significantly larger than the roadway size, this effect is not pronounced. In the engineering case studied in this research, the thickness of the pillar is approximately linearly positively correlated with the safety factor of the pillar approximately linearly negatively correlated with the recovery rate. Overall, this research explored the application of the complex variable function theory in an underground mine design, demonstrating its accuracy and practicality.

Legal Policy for Community Welfare Based Mining Management

This paper focuses on community welfare-based mining management legal policies with the aim of improving the welfare of communities around the mine. The research method used is normative legal research with a statutory approach, case approach and conceptual approach. The results of the research show that the legal policy for managing metallic mineral mining in improving the welfare of communities around the mine is based on four main pillars, namely legal policy for democratic mineral and coal mining management, mineral and coal mining governance using good governance performance standards. Realizing social justice in the fifth principle of Pancasila, and monitoring and enforcing the law against perpetrators of environmental destruction and pollution in the mining sector. The concept of managing metal mineral (nickel) mining based on the welfare of communities around the mine involves regulations regarding licensing, land use, regional development, CSR programs, and participation of local communities in community development programs implemented by mining companies.

Mineral assemblages from chromitites of the Alapaevsk dunite-harzburgite massif (Middle Urals)

Research subject. Minerals and mineral assemblages of noble elements in chromitites of the Alapaevsk massif. Aim. A systematic mineralogical study of high-chromium (Cr) and alumina-rich (Al) chromitites with the development of a sequence scheme for mineral formation, including platinum-group minerals (PGMs) and gold alloys. Materials and Methods. Samples of high-Cr and Al chromitites from chromite deposits in various parts of the Alapaevsk massif. Scanning electron microscopy (Tescan VEGAII XMU and JSM-6390LV Jeol with EDX INCA Energy 450 X-Max 80 spectrometers) and electron microprobe analysis (Cameca SX 100 with five wave spectrometers) were used. Results. A diagram showing the sequence of mineral formation in chromitites was designed; primary and secondary mineral assemblages were distinguished, with the latter assemblage being divided into early and late mineral associations. Primary assemblages of high-Cr (Cr2O3 > 50 wt %) and Al (Cr2O3 < 50 wt %) ores are represented by similar minerals, including chromespinel, clinopyroxene, and olivine, with characteristically distinct compositions of these minerals in each type of ores. Minerals of the primary assemblage are synchronous with chrome-spinel and are represented by pentlandite, Cu-bearing pentlandite, chalcopyrite, pyrrhotite, bornite, as well as PGMs (laurite RuS2, erlichmanite OsS2, native osmium) and Cu-rich gold. Minerals of the secondary early association occur in the form of polyphase inclusions within chrome-spinel. Polyphase inclusions are composed of Cr-bearing chlorite, amphibole, garnet, sulfides (millerite, heazlewoodite) and minerals of native elements, including (Ni, Cr)-bearing copper, nickel-bearing copper, (Cu, Fe, Cr)-bearing nickel, awaruite. Noble metal minerals from the secondary early association were found only in Al chromitites and are represented by laurite, Pt- and Pd arsenides and stibnides, Ru-bearing pentlandite, and high-grade native gold. The secondary late mineral association consists of native copper and awaruite, which are intergrown with serpentine in high-Cr ore. The temperature conditions for the formation of secondary assemblages were estimated using a chlorite geothermometer. The formation temperatures of the studied chlorites from chromitites fall within the range of 250–284°C. Conclusions. Noble metal minerals from secondary associations were formed at temperatures below 350°C together with garnet, amphibole, chlorite, and nickel sulfides. Grains of primary Os–Ir–Ru alloys during epigenetic processes underwent sulfurization with the formation of a fine-grained porous mixture of native and sulfide (sometimes with As) phases, and replacement by Ru-pentlandite. The presence of awaruite and native Cu and Ni in both primary and secondary assemblages of chromotites indicates the reducing conditions for the formation of noble metal minerals. The limited occurrence of high-Cr ores, along with the manifested processes of sulfurization for primary grains of Os–Ir–Ru alloys, led to the scarcity of detrital PGM in the area of the Alapaevsk massif.

Experimental study on the mechanical properties and cementation mechanism of microbial cemented fine tailings backfill

The extensive exploitation of metal mines has resulted in the generation of vast quantities of fine tailings, posing significant environmental challenges such as surface subsidence and deposition. The conventional cemented backfill technology, which has been widely used for tailings processing, requires substantial cement consumption and thus leads to escalated economic costs and carbon emissions. In this paper, we propose a pollution-free alternative, Microbial-Induced Calcite Precipitation (MICP) technology, as a promising solution for sustainable mine filling. The study employs microscopic and macroscopic analysis techniques, including laser diffraction particle size (LDPS) analysis, scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), to investigate the inner structure and mechanical properties of the microbial cemented fine tailing backfill (MCFB). Key parameters such as unconfined compressive strength (UCS), CaCO3 content and porosity are examined, with a focus on the effects of bacterial solution dosage and curing time. The results reveal that the MICP-processed fine tailings exhibit an increase in particle size by approximately 292.1% compared to their original size. Furthermore, MCFB specimens demonstrates significantly enhanced UCS and decreasing porosity under comparable conditions, surpassing the performance of traditional cemented fine tailings backfill (CFB) specimens. Microscopic analysis highlights that the strength development in MCFB predominantly arises from the cementation effects of MICP-induced CaCO3, primarily in the form of calcite, rather than the cementation effects resulting from hydration products (C-S-H) in conventional CFB.

How circular is an extractive economy? South Africa's export orientation results in low circularity and insufficient societal stocks for service-provisioning

The circular economy is a major topic in import-dependant nations like Japan, China or the European Union, where supply security, strengthening domestic value chains and greening economic growth are key concerns. In contrast, extractive economies, mostly in the Global South, provide resources to the world market and thus exhibit inherently linear resource use while struggling for sustainable development. Circularity in resource importing regions could undermine extraction-based development modes, but such effects have rarely been studied yet.Herein, we analyse economy-wide circularity for all flows of materials, energy, waste and emissions in South Africa, for the year 2017. We advance an established methodology regarding interlinked metals mining, constraints to sustainable biomass cycling, and informal disposal, waste picking and informal and formal reuse. Data were developed from national and international sources, and reviewed and co-produced with national experts in an online workshop series.Cornerstones of South Africa's biophysical economy in 2017 are a domestic extraction of 875 Mt, low imports of 32 Mt dominated by oil, 170 Mt of exports dominated by coal and metal ores, resulting in 496 Mt of total waste and emissions. Processed material is 917 Mt or 16 t/cap (EU27: 16 t/cap). Materials use for stock-building is very low at 130 Mt (2.3 t/cap). Socioeconomic input cycling is only 2 % [1.4–2.8 %] and ecologically sustainable biomass cycling is only 4 % [3.9–6.1 %], totalling 6 % input circularity. Given the low circularity, we conclude on leverage points for a transformation towards increased circularity to yield socio-economic benefits in a highly unequal society.

Risk assessment and rare metals mineralization associated with alteration aspects of Rhyolite flow tuffs, Egypt

Argillic alteration and hematitization are the two extensive alterations that affected Um Safi rhyolite flow tuffs. Rare metal mineralization including radioactive minerals (thorite, uranothorite), Nb-bearing minerals (columbite, yettrocolumbite, Nb-rutile), zircon, REE-minerals (LREE-carbonate, xenotime) as well as molybdite, pyrite, fluorite, hematite and ilmenite have been identified by using Energy Dispersive Spectrometer (EDS) and are well recorded in argillic and hematitized samples. The investigated rhyolite flow tuffs show that the activity concentration of radionuclides changed from 1.2 to 453.2 Bq kg−1 for 238U, from 3.2 to 489.6 Bq kg−1 for 232Th, and from 31.3 to 88954.6 Bq kg−1 for 40K. The mean values of 238U, 232Th, and 40K activity concentrations are 90.8 ± 84.5, 122.9 ± 90.5 and 6286.7 ± 1562.2 Bq kg−1, respectively. The hazard factors are estimated. Their results exceeded the recommended limit. Thus, the investigated rhyolite flow tuffs are not safe to use in building materials and other construction industries. A multi-statistical approach is performed to show the correlation between the radioactive concentration and radiological hazard factors. This approach illustrates the positive correlation between uranium and thorium due to their contribution from the natural radioactive series—moreover, a strong correlation was obtained between potassium and all radiological parameters. Thus, the radioactive hazards impact in the present study is related to the presence of radioactive minerals such as thorite and uranothorite in addition to other accessory minerals.

Влияние природного выщелачивания руд на заболеваемость населения селитебных территорий

The problem of prevention of contamination of the residential area of metal mines by extracting metals from natural leaching solutions to reduce the incidence of residents is considered. Quantitative indicators are presented concerning the pollution of residential areas with natural leaching products. It is proposed to extract toxic metals from the liquid leaching products as they reach the earth surface. The mechanism of environmental degradation as a result of the activities of the enterprises of the Sadon lead-zinc plant is detailed. It is shown that the phenomenon of extraction of metals from natural and technological solutions can be used in the implementation of environmental protection processes. The results of the application of geotechnological methods of metal production in the North Caucasus are summarized. The contribution of scientists from the North Caucasus Mining and Metallurgical Institute to the theory and practice of metal leaching is noted. The program of technological and medical research was developed, and the results of comprehensive studies of the morbidity of mine workers and residents of residential areas depending on the distance from the source of pollution are presented. An algorithm for the organization of preventive leaching of ores left in the worked-out space is proposed. It is proved that the chemical impact of natural leaching of ore mining and processing products on the population of residential areas is the cause of technogenic metal-induced toxicity and is accompanied by an increase in diseases. It is substantiated that a radical measure to prevent progressive morbidity is the preventive extraction of metals from ore processing tailings and mine wastewater. It is shown that the extraction of metals from the products of their activities helps to reduce environmental damage and morbidity among employees of mining enterprises and the population of residential areas.

Development of a mixed reality assisted escape system for underground mine- based on the mine water-inrush accident background

The underground mine is an essential infrastructure for national resources and economy, and its safety system is an important issue, especially the miners’ safety. They should not only enhance their preventive awareness of disasters but also enhance their response capability. When miners are in danger with invalid escape lighting, it is difficult for them to overcome panic. Therefore, the automatic assisted escape system has a particular engineering significance in underground space. This study attempts to develop a reference technical framework for emergency evacuation of underground space workers. A human-environment-computer interaction system is developed, which combines the A*-3D Time algorithm with mixed reality (MR) technology. It is constrained by the spatial geometric information of the mine and the escape time. Firstly, the target mine’s geographic information and spatial structure are surveyed on the field, and a 3D digital model is built by the 3DMine; the BIM is used to integrate 3DMine information (data and material) and design the spatial structure. Secondly, based on the A* algorithm in 3D space, the escape time is introduced to evaluate the escape capability and construct the A*-3D Time model. Thirdly, the timeliness of mine water-inrush scenario is simulated by the Comsol; the interaction method and navigation map are developed by the OpenXR and MR Toolkit (MRTK) in Game Engine; the A*-3D Time model is introduced into the C# script and assigned to the digital objects (Mine and Miners). Finally, the performance of this system is analyzed based on the underground metal mine. Based on game thinking to solve safety problems can be used as a reference for underground space engineering.

Comprehensive Environmental and Health Risk Assessment of Soil Heavy Metal(loid)s Considering Uncertainties: The Case of a Typical Metal Mining Area in Daye City, China

Heavy metal(loid)s (HMs) in soils near mining sites often cause serious environmental and health issues. Accurately assessing soil HM risks and identifying priority pollutants are crucial for improving risk control efficiency with limited management costs and resources. Traditional deterministic assessments may yield biased results due to the imprecision and ambiguity of environmental data and assessment processes. To compensate for the deficiencies of deterministic assessment, a comprehensive probabilistic-fuzzy model was developed based on fuzzy theory, probability methods, the soil contamination risk (SCR) index, and a human health risk (HR) assessment framework. According to this model, the soil HM risk status in a typical mining area in China was evaluated. The results indicated that Cd and Cu significantly violated the relevant environmental guidelines and were considered priority metals for environmental risk (ER). Notably, Cd’s hazard predominantly manifested in a solid potential ecological risk (PER), whereas Cu’s environmental impact primarily manifested as a soil contamination risk (SCR). From the perspective of HR, soil HMs already pose a considerable threat to human health, with children facing greater HRs than adults. As was identified as a priority element for HRs, with carcinogenic and non-carcinogenic risks reaching unacceptable levels. Regarding general risk (GR), Cd and Cu ranked in the first gradient and As in the second gradient. Overall, the accumulation of soil HMs—especially Cd, Cu, and As—in the study area has posed a significant threat to the ecosystem and human health. The risks of other HMs (Pb, Zn, Cr, and Ni) are relatively low, but the superimposed risks of multiple HMs should not be ignored. The probabilistic–fuzzy model reduces the uncertainty of risk assessment, and the model integrates the environmental and health risks of HMs, providing more comprehensive risk information. The assessment results can serve as a reference for managers to develop targeted control strategies.

Going beyond carbon: An "Earth system impact" score to better capture corporate and investment impacts on the earth system

Corporations are responsible for a significant portion of observed impacts on the Earth system, including green-house gas (GHG) emissions, but also water extraction, landuse change and other pressures on nature. These nature-related impacts are essential to consider and capture because they have local impacts on a range of ecosystem functions on which companies and economies depend, but they also fundamentally affect our ability to mitigate and adapt to a changing climate. Furthermore, climate, land and water interact and affect each other in various ways, such that climate change can be exacerbated by degraded ecosystems, which in turn are dependent on water.This paper tests a novel metric developed to capture corporate Earth system impact (ESI) beyond merely direct GHG emissions and explores how such a tool could be used to improve assessments of corporate environmental impacts and support decisions on where to direct public and private investments. We use the mining sector as a test case to illustrate the applicability of the ESI score and examine the impact of the the five largest (by market cap) mining companies in the precious metal mining sector and the top five in the non-precious metal mining sector. We find that many of the mining assets have non-negligible impacts on land and water, and we show that the ESI metric identifies a different set of asset for targeted action than conventional carbon intensity scores would do.

KARAKTERISTIK MINERALOGI PADA VEIN TEMBAGA KLUWIH, PACITAN, JAWA TIMUR

The southern mountains of Java are a path of copper-gold mineralization that has proven to have high economic value. Pacitan is part of the geological system and mineralization of the southern mountains, which are part of the Sunda Arc magmatism. The research area is located in the copper mining location in Kluwih village, Tulakan, Pacitan, East Java. The presence of copper mineralization in the form of massive sulfide/sulfosalt veins in the Kluwih area is evidence of an epithermal mineralization system which is rare and has not been studied intensively. This study intends to carry out mineralogical tests both physically and chemically for the characteristics and mineralogical composition of vein in the Kluwih area. The research was conducted using geological mapping methods in mine tunnels, rock sampling, laboratory analysis using petrographic methods, ore microscopy, rock geochemistry using ICP OES/MS – XRF – AAS, mineralogy using SWIR and XRD spectral analysis. The geomorphology of the Kluwih area and its surroundings consists of the morphology of alluvial plains and intrusive hills. Lithology is composed of volcanic–subvolcanic rocks in the form of porphyry dacite, dacite, dacite breccia, and alluvium. Mineralization forms in structural openings that cut and alter dacite rocks and dacite breccias. The alteration that develops in the Kluwih area, especially in the area around the mine (tunnel) is dominated by kaolinite-illite, pyrophyllite-little-sericite, chloritization, and mineralization found in the form of veins that have massive sulphide composition with the dominant internal texture being breccia. The texture or structure of the mineralization is in the form of brecciation (hydrothermal breccia), sulfide-pyrophyllite-kaolinite, quartz- sulfide/sulfosalt, and massif sulfide/sulfosalt. The results showed that the ore had a density of 4.65 gr/cm3 while the highly argillic altered side rocks had a density of 2.54 gr/cm3. In the ore, visible massive sulfide/sulfosalt minerals consist of mosaic bonds and intergrowth between similar or different minerals. The detected ore minerals are pyrite, enargite, covellite, chalcopyrite, and bornite. Enargite and pyrite are the dominant metallic minerals found in ores. Enargite crystals appear to have a size of 56 - 160µm, pyrite accumulates in anhedral crystal forms with a size of 120 - 900µm and inclusions in enargite measuring 50 - 140µm, along with covellite-chalcopyrite ± bornite minerals with a fine size of 5 - 20µm. The geochemistry of the ore is seen as sulfide filling, as evidenced by the SiO2 value of only 4.5% followed by metal enrichment in the form of 27.6% Fe, 12.6% Cu, 4.15% As, and 46.2% S. Alteration minerals which is present is probably a mica group such as phengite with a marked presence of elements of 0.7% MgO and 1.9% Al2O3. The geochemistry of the side rock is seen to have a high SiO2 value of 71.7%, followed by a high alkaline element forming alteration minerals such as pyrophyllite with an Al2O3 value of 15.3% with a low total Ca-Na-K value of 0.25%, and there is residual TiO2 by 0.38%. Terraspectral analysis and XRD confirmed that the main peaks were pyrophilite-phengite, followed by the minerals enargite and pyrite. The Kluwih vein is a copper vein associated with advanced argillic alteration, as part of a rich high sulfidation epithermal system with Cu-Au-As-Sb mineralization.

Spectral induced polarization responses of carbonate precipitation in gel-saturated media with and without electron conductors

SUMMARY Interest in the use of carbonate precipitation for the purposes of soil stabilization, carbon capture and environmental remediation has created a need for geophysical techniques capable of characterizing the 3-D extent of precipitation in the subsurface. The use of spectral induced polarization, a geophysical technique sensitive to mineral precipitation and dissolution processes, has been investigated in previous studies; nevertheless, debate still exists regarding measured induced polarization (IP) signals relating to the formation of calcite. In this study, calcite was precipitated within gel-saturated media through highly controlled double-diffusion methods. Three experiments were conducted to study both the inherent IP response of calcite in isolation, as well as the IP response when precipitated within a low-polarizability background medium (quartz sand) and a high-polarizability medium (a sand–magnetite mixture). The results support that in isolation, the polarization of the electrical double layer surrounding individual calcite grains is not a significant contributor to IP signatures from calcite precipitation. However, under certain circumstances the precipitation of calcite, in the quartz-sand and sand–magnetite mixtures, can produce a strong IP response when the precipitation blocks a current conduction pathway. If metallic mineral grains are present then they may act as conduits for current if they become embedded in an insulating calcite wall, creating a significant electrode polarization which dominates the IP signal. Equivalent circuit models indicate that the precipitation of calcite as a thin planar front normal to the current path is analogous to a simple lossy capacitor blocking most DC current but being thin enough to measurably polarize. Circuit models also suggest that the total impedance seen from the sand–magnetite sample is simply the sum of the impedance of the disseminated grains and the grains encased in the calcite front. The encased grains also have a higher relaxation time which may indicate a different polarization mechanism than from disseminated magnetite.

Assessment of heavy metals bioaccumulation in Silver Birch (Betula pendula Roth) from an AMD active, abandoned gold mine waste.

Acid mine drainage (AMD) is generally outlined as one of the largest environmental concerns, characterized by very low pH value of mine waste, heavy metals and high sulphate content. This extremely hostile environment reduces plant ability to develop and grow. Present study focuses on a silver birch (Betula pendula Roth), a pioneer species that grows on an extremely hostile gold mine waste, to investigate the bioaccumulation of rare metals (thallium (Tl) and indium (In)), as well as nine other more common heavy metals (bismuth (Bi), cadmium (Cd), cobalt (Co), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), silver (Ag) and zinc (Zn)), and to asses phytoextraction and phytostabilization potential of silver birch. Additionally, parameters determining AMD process and overall contamination (pH, electrical conductivity (EC), sulphates (SO42-), arsenic (As), iron (Fe), oxidation-reduction potential (ORP), turbidity, dissolved oxygen (DO), total dissolved solids (TDS), acidity, hardness, X-ray diffraction (XRD) and radioactivity) were determined in mine waste and drainage water samples. To assess the heavy metals bioaccumulation and mine waste status, statistical geochemical indices were determined: bioaccumulation factor (BCF), pollution load index (PLI), geochemical abundance index (GAI) and exposure index (EI). The results show that silver birch bioaccumulates the essential elements Cu, Ni, Mn and Zn, and the nonessential elements Tl (average BCF = 24.99), In (average BC = 23.01) and Pb (average BCF = 0.84). Investigated mine waste was enriched by Bi, Ag and Cd according to positive values of GAI index. Present research provides a novel insight into bioaccumulation of nonessential heavy metals in silver birches who grow on the extremely hostile mine waste, and they exhibit significant phytoremediation potential.

Metal mining waste could impact millions

Metal mining waste could impact millions

Dual role of birnessite on the modulation of acid production and reinforcement of interspecific electron transfer in anaerobic digestion

Achieving efficient anaerobic digestion of highly loaded substrates is one of the most challenging problems in the field of waste resourcing. Here, the addition of birnessite (2.0 g/L) to kitchen wastewater increased the acetate and final methane yields by 40.53 and 99.18 %, respectively, while reducing the yields of propionate and butyrate by 38.17 and 48.86 %, respectively. There were two main pathways for birnessite to enhance anaerobic digestion, one of which is to act as an electron acceptor, by inducing an alteration in the ratio of reduced-state coenzyme I in the microorganism, allowing the acid production process to proceed towards deeper oxidation. Another pathway enhances the interspecific electron transfer between bacteria and archaea and improves methane yield by optimizing the metabolic relationship. The Kyoto Encyclopedia of Genes and Genomes (KEGG) functional predictions suggest that the extracellular electron transport pathway of the microorganism is enhanced with the addition of birnessite and that its intracellular metabolic pathway is biased towards the nicotinamide adenine dinucleotide (NADH) generation pathway. This work demonstrated that anaerobic digestion facilitation by metallic minerals was not monolithic; that is, different properties of the minerals were employed to intensify the different stages of anaerobic digestion and obtain an amplification cascade.

Lithium isotopic systematics and numerical simulation for highly-fractionated granite-pegmatite system: Implications for the pegmatite-type rare-metal mineralization

Lithium (Li) isotope behavior during fractionation of highly-evolved granitic pegmatites and associated rare metal mineralization remains unclear, especially concerning the relative importance of magmatic versus metasomatic processes. In this study, we investigated the geochemistry and Li isotopes of the giant Renli-Chuanziyuan lithium-niobium-tantalum (Li-Nb-Ta) deposit in the Mufushan batholith (South China). We found that muscovite granite in the Mufushan complex can be divided into two groups (high-Li and low-Li). δ7Li value of the high-Li and low-Li group increases and decreases, respectively, with increasing Li content, which is likely resulted from fractional crystallization and/or magmatic volatile phase (MVP) exsolution. The MVP exsolution began with the solidification of muscovite granite, as evidenced by the zoned micas. The Li isotope fractionation, modeled by Rayleigh distillation during MVP exsolution, is consistent with the δ7Li value of Li-poor pegmatite, indicating that MVP exsolution is related to the pegmatite formation.The Mufushan Li-poor and Li-rich pegmatites have very high and low δ7Li value, respectively. Based on the Δ7Li(bulk-mica) value and numerical simulation, we suggest that the pegmatite formation at Mufushan could be linked to extensive MVP accumulation, while the different Li elemental and isotopic compositions of the two types of pegmatite are probably caused by MVP migration. In fact, published granite-pegmatite data worldwide also show negative Li vs. δ7Li correlation, indicating that such MVP exsolution, accumulation and migration are probably a common phenomenon for evolution of granitic pegmatite. Therefore, the different Li isotopes and Li-Rb-Cs proportion of Li-poor and Li-rich pegmatites indicate that MVP exsolution, migration and accumulation are key to rare metals enrichment and distinguish various types of rare-metal mineralization (Li and Nb-Ta).

Heavy Metal and the Mineral Ions Assessment of Borehole Water Used in Port Harcourt Oil Refinery Host Communities

This study presents the findings of an assessment conducted to determine the levels of heavy metals and mineral ions in borehole water used in the Port Harcourt oil refinery host communities. The study area comprised six selected communities located in the vicinity of the oil refinery in Rivers State, Nigeria. Water samples were collected from various boreholes in each community and analyzed for heavy metal concentrations and mineral ion content within the World Health Organisation (WHO) and National Standard for Drinking water Quality (NSDWQ) standard. The results revealed significant variations in heavy metal and mineral ion levels across the selected communities, with some areas exhibiting elevated concentrations of lead, arsenic, and cadmium. These heavy metals are known to pose health risks to humans, even at low concentrations, and raise concerns about the safety of the borehole water for consumption and agricultural use. It is highly recommended that borehole water in Port Harcourt Refinery be properly and routinely investigated as well as other water parameters checked. And Nigerian government in partnership with Non-governmental organization should conduct water security mapping to help identify vulnerable areas (communities) where there is high water stress such that the areas are given priority in borehole allocation

MAGNEX and PILCCU in Finland: deployment of CO2 mineralisation in circular economies

Two ongoing projects in Finland, MAGNEX (Viable magnesium ecosystem: exploiting Mg from magnesium silicates with carbon capture and utilization) and PILCCU (Piloting of ÅA CCU) aim at using CO2 mineralisation technology for the overlapping purposes of large-scale CO2 emissions mitigation and bringing several valuable material streams into circular economies, including construction. Of central importance are magnesium-based materials, such as magnesium carbonate hydrate (MCH), besides (amorphous) silica and several metallic species. On top of revenues from these, CO2 emissions mitigation lowers the financial penalty from CO2 emission rights under for example the European ETS. The ÅA process routes are stepwise processes based on extraction of magnesium (and other species) from serpentinite-containing mining tailings from Finland, followed by precipitation of metallic species, carbonation using a CO2 containing gas-stream (no separate capture step needed) and recovery of solvent salt, respectively. Several separation steps involve (ion-selective) membrane electrodialysis. Besides ongoing mapping and characterisation of Finnish rock resources as tailings or other side-streams at metal and mineral mines in Finland, the projects address public acceptance, legislation and other non-technical issues related to large-scale roll-out of this type of CCU technology.For the use of the solids, magnesium-based cement binders and plaster-like recipes are investigated as well as applications for the (amorphous) silica and other residues, including the use of MCH for cyclic thermal energy storage (TES). Special focus is on accelerating the carbonation step and the final outcome of MCH production, considering pressure (including supercritical CO2 levels), and the role of recoverable catalysts and other additives. The work receives funding from the Academy of Finland (2022-2025) and from Business Finland plus industry partners (2022-2024), respectively.

Effect of a Double-Machine Parallel Air Curtain on Wind Flow in an Underground Roadway of a Coal Mine

In order to study the effect of a double-machine parallel circulation air curtain in intercepting wind flow in a mine roadway, the air curtain jet angle and full fan pressure were analyzed. Taking a metal mine roadway as the engineering background, Fluent numerical simulation technology was used to establish an equi-proportional physical model of the original roadway, and a K45-6 axial flow fan was selected to numerically simulate the flow field inside the original roadway, which was analyzed from three aspects: isolation pressure difference, air leakage volume and wind choke rate. The results show that when the full pressure of the fan is fixed, with an increase in the jet angle of the air curtain, the separation pressure difference and the wind choke rate show a trend of first increasing and then decreasing, and the air leakage volume shows a trend of first decreasing and then increasing. With an increase in the air curtain jet angle, the air curtain convergence gradually forms a complete air curtain, but when the air curtain jet angle continues to increase, the air curtain cannot effectively block the wind flow due to the transverse pressure from the roadway. When the jet angle is too small or the full pressure of the fan is too large, the phenomenon of induced air flow will occur, and the two-machine parallel air curtain will direct the air downstream of the roadway to upstream and no longer intercept the roadway air flow. After comprehensive analysis, the effect of wind control is obvious to set up a double-parallel air curtain in the roadway, and the optimal combination of the roadway air curtain is 30° for the full pressure blade of the fan and 30° for the jet angle.

Distribution heterogeneity of sediment bacterial community in the river-lake system impacted by nonferrous metal mines: Diversity, composition and co-occurrence patterns

Metal(loid) pollution caused by mining activities can affect microbial communities. However, knowledge of the diversity, composition, and co-occurrence patterns of bacterial communities in aquatic systems impacted by nonferrous metal mines. Here, the metal(loid) contents and bacterial communities in sediments from the Zijiang River (tributary to mainstream) to Dongting Lake were investigated by geochemical and molecular biology methods. The results indicated that the river sediments had lower pH and higher ecological risk of metal(loid)s than the lake sediment. The diversity and composition of bacterial communities in river sediments significantly (p < 0.05) differed from those in lake sediments, showing distributional heterogeneity. The biomarkers of tributary, mainstream, and lake sediments were mainly members of Deltaproteobacteria, Firmicutes, and Nitrospirae, respectively, reflecting species sorting in different habitats. Multivariate statistical analysis demonstrated that total and bioavailable Sb, As, and Zn were positively correlated with bacterial community richness. pH, TOC, TN, and Zn were crucial factors in shaping the distribution difference of bacterial communities. Environment-bacteria network analysis indicated that pH, SO42−, and total and bioavailable As and Sb greatly influenced the bacterial composition at the genus level. Bacteria-bacteria network analysis manifested that the co-occurrence network in mainstream sediments with a higher risk of metal(loid) pollution exhibited higher modularity and connectivity, which might be the survival mechanism for bacterial communities adapted to metal(loid) pollution. This study can provide a theoretical basis for understanding the ecological status of aquatic systems.