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Heavy metals mainly exist on the surface of sediment particles and are transported using particulate matter as carriers. Therefore, the particle size of sediment particles can affect the adsorption, release, and migration of heavy metals. This study aim to investigate the distribution characteristics and chemical fraction of Cd, Pb, and As contents in sediments of different particle sizes using the BCR method, and to determine the key factors affecting the distribution of heavy metals through mineralogical methods such as XRD and EDS. The results revealed that the overall content of various forms of heavy metals increases with the decrease of particle size, mainly presents in fine particles. The mineralogical analysis results indicated that fine particles predominantly contained clay minerals such as chlorite and illite and coarse particles mainly include primary minerals. Due to the mining areas in the middle-upstream, Cd, Pb and As were primarily associated with galena, sphalerite and pyrite, respectively. The distribution of heavy metals is jointly influenced by sediment particle size and sediment material composition. [ABSTRACT FROM AUTHOR]

Germanium (Ge) is a critical raw material for emerging high-tech and green industries, resulting in considerable recent interest in understanding its distribution and geochemical behavior in ore deposits. In this contribution, the distribution of Ge and related trace elements in the Fule Pb-Zn(-Ge) deposit, South China, is investigated to reveal the distribution of Ge in the hydrothermal ores and during sulfide weathering, using multiple microanalytical techniques, including scanning electron microscopy, electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the Fule MVT deposit, sphalerite (ZnS) is the most significant Ge-carrier relative to other sulfides, though the five recognized textural types of sphalerite display progressive depletion in Ge from the first sphalerite generation to the late one. In the early stage, sphalerite with fine-grained chalcopyrite inclusions has the highest Ge concentrations, probably accounting for a significant proportion of the total Ge. We interpret that high Ge concentrations in the early sphalerite may be attributable to high Cu activity in the mineralizing fluids. During oxidative weathering, Ge was redistributed from its original host, sphalerite, to the weathering product willemite (Zn2SiO4) rather than smithsonite (ZnCO3), with high levels of Ge (up to 448 μg/g) present in the willemite. The formation of abundant willemite largely prevents the dispersion of Ge during weathering. In principle, willemite-hosted Ge should be fully recoverable, and the Zn-silicate ores may, therefore, be a potential target to meet future demand. This study provides new information on how Ge behaves from sulfide- to weathering-stage in MVT systems, which directly impacts Ge mobility and deportment changes and the development of metallurgical strategies for Ge recovery. [ABSTRACT FROM AUTHOR]

The Paleo-Mesoproterozoic North Singhbhum Mobile Belt (NSMB) is a fold-thrust belt typically found in a collisional setting and is well known for hosting gold mineralisation. A study carried out in the northern part of NSMB depicts varieties of acid volcanic rocks along with mica schist, ferruginous cherty quartzite, black shale, and sheared granite, which are all ubiquitously traversed by quartz veins/reefs. In the study area, gold mineralisation is mostly restricted to brecciated quartz reef occurring ENE–WSW along S1 foliation, which also depicts syn to late kinematic brittle–ductile shearing. The petrographic studies of mineralised cherty variant of quartzite in quartz reef depict the presence of two generations of the quartz vein. The older one is smoky/bluish, altered, recrystallised and consists of disseminated and stringers of pyrite, chalcopyrite, etc., whereas the younger veins are milky white and lack mineralisation. The presence of pyrite–pyrrhotite and chalcopyrite–pyrrhotite associations and conversion of pyrite to pyrrhotite along fracture depicts prograde metamorphism. Trace elemental mineral chemistry depicts significant Au enrichment in pyrite. A positive correlation between Co and Ni concentrations in pyrite indicates hydrothermal origin. Au–As ratio explains the enrichment of gold in pyrite, where gold occurs as a solid solution in pyrite, which is generally referred to as invisible gold. The presence of gold grains/nuggets at the microscopic level and in pan concentrate as well as considerable analytical value in bulk rock coupled with occurrence in sulphide structure, points towards the bimodal nature of gold mineralisation. Mode of occurrence, nature of mineralisation, and surficial, structural and mineralogical characteristics suggest gold mineralisation of the study area is of orogenic type. [ABSTRACT FROM AUTHOR]

Copper tailings are a common byproduct of copper production, containing high levels of heavy metals which are released into the environment. Conventional methods have historically prioritized copper recovery, and often overlooking the leaching of other valuable elements. However, the rising demand for nonferrous metals necessitates understanding their leaching behavior from copper tailings. This study examined the atmospheric leaching of Cu, Fe, Pb, Zn, and CuO from a polymetallic tailing ore. Leaching recoveries of 63.5% for Cu, 97.5% for CuO, 1% for Fe, and 100% for Zn were achieved under the optimum conditions of 0.5 M sulfuric acid concentration, 25% solids percentage, 65°C, stirring speed of 100rpm, particle size of 75 µm within 30 minutes. Results indicated that the dissolution of oxide minerals such as CuO and ZnO was significant; however, copper sulfides need oxidant to be dissolved. In this condition, iron oxides and silicates were partially reacted by sulfuric acid, and Pb-bearing minerals formed lead sulfate. The presence of iron and lead-bearing minerals in the leaching residue was confirmed by XRF, XRD, and SEM analyses, and was in agreement with the information displayed in the Eh-pH diagrams. [ABSTRACT FROM AUTHOR]

Intermediate sulfidation epithermal deposits represent significant reservoirs of precious metals, playing a crucial role in global mining operations. The Anatolian Peninsula, predominantly characterized by relatively young (Tertiary) lithologies, hosts numerous occurrences of epithermal base and precious metal mineralization. Within the realm of research in Northeastern Anatolia, several hydrothermal alteration zones have emerged as indicators of concealed epithermal mineralization, with the Bahçecik mineralization standing out as a recent focal point. The Bahçecik mineralization represents an intermediate sulfidation epithermal Au-Ag system, hosted by Late Cretaceous andesitic rocks, as well as Eocene dacitic lava and tuffs. Employing U-Pb LA-ICP-MS zircon dating of the dacitic host rocks, the mineralization is estimated to have occurred during the Lutetian epoch (43.61 ± 0.35 Ma) or later. The genesis of the Bahçecik deposit is believed to be linked to postcollisional regional extensional tectonics, primarily controlling its structural arrangement. Comprising pyrite, chalcopyrite, low-Fe sphalerite, galena, tetrahedrite/tennantite, enargite-luzonite, and gold-silver minerals, the deposit is accompanied by prominent gangue minerals such as Mn- and Ca-carbonates, quartz, and barite. Microprobe measurements have identified a majority of Au-Ag minerals (krennerite, buckhornite, and nagyagite) closely associated with sulphide minerals. Fluid inclusion data reveal that mineralization and fluid transportation occurred at temperatures ranging from 153 to 327°C, with solutions exhibiting salinity levels consistent with those of intermediate sulfidation deposits (1.7–7.3 wt.% NaCl). This study unequivocally classifies the Bahçecik mineralization as an intermediate sulfidation deposit, contrary to the conclusions drawn in previous research. Moreover, our investigation has unveiled the presence of a substantial ore resource, totalling 7.84 million tons, featuring 1.76 g/t Au and 2.24 g/t Ag. As an intermediate-type deposit, it shares characteristics with other subtypes within the epithermal class, bridging the realms of both high and low sulfidation systems. [ABSTRACT FROM AUTHOR]

Exponential increasing demands for base metals have made meaningful processing of their quite low-grade (>1%) resources. Froth flotation is the most important physicochemical pretreatment technique for processing low-grade sulfide ores. In other words, flotation separation can effectively upgrade finely liberated base metal sulfides based on their surface properties. Various sulfide surface characters can be modified by flotation surfactants (collectors, activators, depressants, pH regulators, frothers, etc.). However, these reagents are mostly toxic. Therefore, using biodegradable flotation reagents would be essential for a green transition of ore treatment plants, while flotation circuits deal with massive volumes of water and materials. Pyrite, the most abundant sulfide mineral, is frequently associated with valuable minerals as a troublesome gangue. It causes severe technical and environmental difficulties. Thus, pyrite should be removed early in the beneficiation process to minimize its problematic issues. Recently, conventional inorganic pyrite depressants (such as cyanide, lime, and sulfur-oxy compounds) have been successfully assisted or even replaced with eco-friendly and green reagents (including polysaccharide-based substances and biodegradable acids). Yet, no comprehensive review is specified on the biodegradable acid depression reagents (such as tannic, lactic, humic acids, etc.) for pyrite removal through flotation separation. This study has comprehensively reviewed the previously conducted investigations in this area and provides suggestions for future assessments and developments. This robust review has systematically explored depression performance, various adsorption mechanisms, and aspects of these reagents on pyrite surfaces. Furthermore, factors affecting their efficiency were analyzed, and gaps within each area were highlighted. [ABSTRACT FROM AUTHOR]

Groundwater quality and availability in coastal aquifers have become a serious concern in recent times due to increased abstraction for domestic, agricultural and industrial purposes. (1) Background: Zhuhai city is selected as a representative coastal aquifer in Southern China to comprehensively evaluate the hydrochemical characteristics, spatial distribution and controlling mechanisms of groundwater. (2) Methods: A detailed study utilizing statistical analyses, a Piper diagram, Gibbs plots, and ion ratios was conducted on 114 surface water samples and 211 groundwater samples. (3) Results: The findings indicate that the pH of most groundwater is from 6.06 to 6.52, indicating a weakly acidic environment. The pH of surface water ranges from 5.35 to 9.86, with most values being weakly alkaline. The acidity in the groundwater may be related to the acidic atmospheric precipitation, an acidic unsaturated zone, oxidation of sulphide minerals and tidal action. The groundwater chemical types are predominantly mixed, followed by Ca-Mg-HCO3 type. Surface water samples are predominantly Na-Cl-SO4 type. The NO3− concentration in groundwater is relatively high, with a mean value of 17.46 mg/L. The NO2− and NH4+ concentrations in groundwater are relatively low, with mean values of 0.46 mg/L and 7.58 mg/L. (4) Conclusions: The spatial distribution of the principal chemical constituents in the groundwater is related to the landform. The chemical characteristics of groundwater in the study area are mainly controlled by the weathering and dissolution of silicate and sulfate minerals, evaporation, seawater mixing and cation exchange. Nitrate in clastic fissure groundwater, granite fissure groundwater and unconfined pore groundwater primarily originates from atmospheric precipitation, agricultural activities of slope farmland and forest land. Nitrate in confined pore groundwater and karst groundwater primarily originates from domestic sewage and mariculture wastewater. Our findings elucidate the processes characterizing the hydrogeology and surface water interactions in Zhuhai City's coastal system, which are relevant to other catchments with similar geological characteristics. [ABSTRACT FROM AUTHOR]

If dihydrogen (H2) becomes a major part of the energy mix, massive storage in underground gas storage (UGS), such as in deep aquifers, will be needed. The development of H2 requires a growing share of H2 in natural gas (and its current infrastructure), which is expected to reach approximately 2% in Europe. The impact of H2 in aquifers is uncertain, mainly because its behavior is site dependent. The main concern is the consequences of its consumption by autochthonous microorganisms, which, in addition to energy loss, could lead to reservoir souring and alter the petrological properties of the aquifer. In this work, the coinjection of 2% H2 in a natural gas blend in a low-salinity deep aquifer was simulated in a three-phase (aquifer rock, formation water, and natural gas/H2 mix) high-pressure reactor for 3 months with autochthonous microorganisms using a protocol described in a previous study. This protocol was improved by the addition of protocol coupling experimental measures and modeling to calculate the pH and redox potential of the reactor. Modeling was performed to better analyze the experimental data. As in previous experiments, sulfate reduction was the first reaction to occur, and sulfate was quickly consumed. Then, formate production, acetogenesis, and methanogenesis occurred. Overall, H2 consumption was mainly caused by methanogenesis. Contrary to previous experiments simulating H2 injection in aquifers of higher salinity using the same protocol, microbial H2 consumption remained limited, probably because of nutrient depletion. Although calcite dissolution and iron sulfide mineral precipitation likely occurred, no notable evolution of the rock phase was observed after the experiment. Overall, our results suggested that H2 can be stable in this aquifer after an initial loss. More generally, aquifers with low salinity and especially low electron acceptor availability should be favored for H2 costorage with natural gas. [ABSTRACT FROM AUTHOR]

Pyrite is the most widely distributed sulfide mineral with a wide range of uses, and pyrite is mainly recovered by means of flotation in practical production, and the commonly used flotation collectors are mainly xanthates with good flotation performance. The adsorption behavior of commonly used collectors ethyl xanthate and butyl xanthate on the surface of pyrite is investigated by using the density functional tight bounding theory (DFTB). The results show that when a single reagent acts on the pyrite surface, butyl xanthate has a stronger effect than ethyl xanthate, and the adsorbed mineral surface shows obvious hydrophobicity. The interaction between ethyl xanthate and butyl xanthate had a stronger effect than that of a single reagent, and the simulation of the flotation environment at ordinary temperature using molecular dynamics revealed that the synergistic adsorption of the two different reagents on the surface of pyrite was more hydrophobic, that is, the synergistic adsorption of the combined collector of ethyl xanthate and butyl xanthate on the surface of pyrite was stronger. The results of the study are of great significance for the synergistic effect between the combined collector and the mineral. [ABSTRACT FROM AUTHOR]

The Pulang giant porphyry Cu-Mo polymetallic deposit is located in the Zhongdian area in the center of the Sanjiang Tethys tectonic domain, which was formed by the westward subduction of the Garze-Litang oceanic slab beneath the Zhongza massif. Chalcopyrite-pyrrhotite-pyrite-molybdenite occurs as disseminations, veins, veinlets, and stockworks distributed in the K-silicate alteration zone in the monzonite porphyry, which is superimposed by propylitization. The chemical compositions of biotite and amphibole analyzed by electron probe microanalysis (EPMA) indicate that the ore-forming magma and exsolved fluids experienced a continuous decrease in the oxygen fugacity (fO2). Primary amphibolite and biotite (type I) crystallized at relatively high temperatures (744–827 °C) and low fO2 (logfO2 = − 12.26 to − 11.91) during the magmatic stage. Hydrothermal fluids exsolved from the magma have a relatively lower temperature (621–711 °C) and fO2 (logfO2 = − 14.36 to − 13.32) than the original magma. In addition, the presence of a high abundance of pyrrhotite and an insufficiency of primary magnetite and sulfate in the ore (i.e., anhydrite and gypsum) indicate that the deposit may be a reduced porphyry deposit. Magma and fluid fO2 results, combined with previous research on magmatic fO2 at the Pulang deposit, indicate that the magma associated with the reduced Pulang ore assemblages was initially generated as a highly oxidized magma that was subsequently reduced by sedimentary rocks of the Tumugou Formation. [ABSTRACT FROM AUTHOR]

A low grade copper gold ore in Mongolia contains 0. 20 g/t gold, 0. 24% copper, 1. 80% sulfur and 1.7% magnetic iron. Copper minerals are mainly the chalcopyrite mineral, a small amount of Bornite and copper blue;The other sulfides are mainly pyrite; Magnetic minerals are mainly magnetite and hematite, which can be recovered comprehensively. Based on the ore properties of low content of target minerals and fine distribution size, the flotation magnetic process of 11 Cu S bulk flotation mixed concentrate regrinding Cu S separation comprehensive recovery of Fe from bulk flotation tailings 11 was recommended, and the closed circuit flotation test obtained a copper gold bulk concentrate containing 20. 30% copper and 11. 44 g/t gold, with recoveries of 86. 00% copper and 69. 40% gold. A final iron concentrate containing 65.34% iron was then obtained by the flotation magnetic process, with recoveries of 23. 80% iron and 91. 70% magnetic iron. Compared with the original process, iron resource in flotation tailings can be comprehensively recovered while copper and gold concentrate grade were significantly improved. [ABSTRACT FROM AUTHOR]

Platinum-group elements (PGEs) have a strong affinity for sulfur and tend to accumulate in the deep continental crust, either concentrated within magmatic Cu-Ni-PGE deposits or dispersed throughout disseminated sulfides. However, PGE enrichment in shallow magmatic-hydrothermal systems implies an obscure link to deep sulfide destabilization, which releases PGEs into ore-forming fluids. To bridge this gap, our study investigates the PGE composition of magmatic sulfides with oxidative textures in dacitic rocks from the southwestern Okinawa Trough. We identified three groups of magmatic sulfides, primarily precipitated as Cu-poor monosulfide solid solution (MSS), which formed at distinct stages of magma evolution from deep to shallow crustal levels. Group A sulfides manifest as small-sized inclusions (<30 μm) within most high-Mg olivines, whereas Group B and C sulfides are larger (50–500 μm) and occur within cognate xenoliths of mafic cumulate rocks and the groundmass of host dacites. Group B and C sulfides exhibit distinct oxidative textures and newly-formed mineral assemblages, including magnetite, hematite, goethite, and magnetite ± pyrite, alongside hydrothermal silicate minerals, respectively. We attribute the oxidation process to the infiltration of orthomagmatic fluids exsolved from mafic magma that had underplated the sulfide-bearing felsic magma reservoir, which was nearly solidified. By comparing the chemical compositions between pristine sulfides and their oxidative remnants, we observed extensive mobilization of Pd, Pt, Cu, Ag, Ni, and Co from the altered sulfides of Group B, while Au enrichment occurred as nanoparticles under high oxidation states. In contrast, Au was extracted along with other mobile metals from the altered sulfides of Group C, with Pt remaining in place under more reduced conditions. These distinct scenarios may lead to the formation of PGE-rich and Au-rich fluids, respectively. The formation of deep crustal MSS and subsequent hydrothermal oxidation under varying redox conditions thus provides a viable mechanism for trans -crustal PGE mobilization and inter-element fractionation, typical of PGE-rich magmatic-hydrothermal deposits. [ABSTRACT FROM AUTHOR]

The discovery of a Cu-Ni sulfide deposit in Langmuri of the Eastern Kunlun Orogenic Belt holds significant geological implications. This study, based on the examination of the metallogenic geological body, metallogenic structure, and metallogenic process characteristics, suggests that the deposit is a magmatic Cu-Ni sulfide deposit formed in the collision of orogenic and post-extension processes of the Late Ordovician. The early mineralization of the deposit was primarily derived from the differentiation of sulfides in the mafic–ultramafic rock (450–439 Ma) of the Late Ordovician, while the late-stage mineralization underwent significant superimposed modification by the magmatic–hydrothermal activity of crustal-contaminated biotite granite (415 Ma). In addition, this article analyzes the measurements of the geochemical studies of sediments, and the magnetic and gravity measurements carried out in the area, focusing on the geochemical and geophysical anomaly characteristics in the study area, and selects favorable exploration areas, which have been confirmed to have multiple mineral bodies. By integrating comprehensive gravity, magnetic, induced polarization, and audio-frequency magnetotelluric profile measurements, this study analyzes delineated mineralized zones and the deep extensions of surface mineral bodies to assess deep mineralization potential and identify deep ore-finding targets. It suggests that diverse and scattered mafic–ultramafic complexes in the Langmuri mining area have a large-scale distribution of ore-bearing rocks in the deep. Through the analysis and inverse of the geophysical data, a deep mineralization predictive model was established in the basic–ultrabasic rock mass. The study presents prospects for the delineation of the deep-seated mineralization in the Langmuri deposit. [ABSTRACT FROM AUTHOR]

An enrichment in nickel (Ni) or platinum group elements (PGE) is seldom observed in ores of the iron oxide–copper–gold (IOCG) type. This phenomenon is, however, known from a few deposits and prospects in the Carajás Mineral Province, Brazil. The Ni-PGE enrichment is explained, in part, by the spatial association of the IOCG-type ores with altered mafic-ultramafic lithologies, as well as by reworking and remobilization of pre-existing Ni and PGE during multiple mineralization and tectonothermal events across the Archean-Proterozoic. One such example of this mineralization is the Jatobá deposit in the southern copper belt of the Carajás Domain. This is the first detailed study of the Ni and PGE mineralization at Jatobá, with implications for understanding ore genesis. Petrographic and compositional study of sulfides shows that pyrite is the main Ni carrier, followed by pyrrhotite and exsolved pentlandite. Measurable concentrations of palladium (Pd) and platinum (Pt), albeit never more than a few ppm, are noted in pyrite. More importantly, however, the trace mineral signature of the Jatobá deposit features several platinum group minerals (PGM), including merenskyite, naldrettite, sudburyite, kotulskite, sperrylite, and borovskite. These PGM occur as sub-10 µm-sized grains that are largely restricted to fractures and grain boundaries in pyrite. All Pd minerals reported contain mobile elements such as Te, Bi, and Sb and are associated with rare earth- and U-minerals. This conspicuous mineralogy, differences in sulfide chemistry between the magnetite-hosted ore and stringer mineralization without magnetite, and microstructural control point to a genetic model for the sulfide mineralization at Jatobá and its relative enrichment in Ni and PGE. Observations support two alternative scenarios for ore genesis. In the first, an initial precipitation of disseminated or semi-massive Ni-PGE-bearing sulfides took place within the mafic rock pile, possibly in a VHMS-like setting. Later partial dissolution and remobilization of this pre-existing mineralization by mineralizing fluids of IOCG-type, possibly during the retrograde stage of a syn-deformational metamorphic event, led to their re-concentration within magnetite along structural conduits. The superposition of IOCG-style mineralization onto a pre-existing assemblage resulted in the observed replacement and overprinting in which PGE combined with components of the IOCG fluids like Sb, Bi, and Te. An alternative model involves leaching, by the IOCG-type fluids, of Ni and PGE from komatiites within the sequence or from ultramafic rocks in the basement. The discovery of PGM in Jatobá emphasizes the potential for additional discoveries of Ni-PGE-enriched ores elsewhere in the Carajás Domain and in analogous settings elsewhere. [ABSTRACT FROM AUTHOR]

Tunnel waste constitutes a prevalent by‐product of highway construction in high‐altitude mountainous and hilly regions. Sulphide minerals exhibit a unique distribution pattern within the alpine hills. Consequently, tunnel excavation can disrupt the stability of these sulphide minerals, rendering the tunnel waste susceptible to generating secondary environmental hazards during stockpiling. This research delves into the migration and transformation dynamics of potential environmental pollutants in tunnel waste through geoenvironmental simulation techniques. Controlled variables were employed to simulate various conditions, including surface illumination, internal anaerobiosis, water content and aerobic environments. The study's findings indicate that the presence of pyrite in the waste stream primarily drives the secondary contamination of the tunnel waste. Pyrite within the slag tends to react and form sulphuric acid in the stockpile environment, thus creating an acidic milieu that exacerbates the release of existing contaminants. The emergence of an anaerobic environment and a photocatalytic system composed of Fe/Ti substances in the waste stream serves to further accelerate pollutant release. This study thoroughly investigates the primary causes of environmental pollution during the stockpiling of tunnel slag and assesses the potential environmental impact scenarios. The outcomes of this research offer substantial theoretical and empirical support for the management of slag generated during the tunnel construction process. [ABSTRACT FROM AUTHOR]

Silver isotopes have been extensively used in environment, archaeology, and economic geology. Nevertheless, accurate analysis of Ag isotope ratios faces challenges caused by the presence of matrix elements (e.g. Zn, Cu, and Pb) in most sulfide samples due to isobaric and polyatomic interferences during multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) routines. Most of these elements, such as Cu and Pb, can be effectively removed after the first column through a tandem column setup. However, the complete removal of Zn from Ag remains a significant unresolved issue, particularly given their common coexistence in sulfide minerals. Combining previous studies and the chemical principle of ion exchange resin, we optimized a twostage ion exchange procedure by meticulously adjusting solution volumes and the column separation process. A condensed Zn-doped NIST SRM (silver international standard reference material) 978a was tested for AG50W-X8 resin following our modified procedure, resulting in distinct elution curves of Ag and Zn. Subsequently, three sphalerite samples were selected for the optimized two-stage ion exchange procedure, and ICP-MS results of silver elution fractions demonstrated complete separation of Ag and Zn. The whole procedure achieved an Ag yield exceeding 98.1 ± 2.3% (2SD, n = 4). NIST SRM 978a and IAEA-S-1 (an inhouse standard) were tested for long-term reproducibility with -0.001 ± 0.030& (2SD, n = 25) and 0.054 ± 0.023& (2SD, n = 22) of d109Ag, respectively, indicating the high accuracy in MC-ICPMS routines. Zn-doped NIST SRM 978a and sphalerite samples were further subjected to the modified procedure, and they exhibited values of 0.004 ± 0.014& (2SD, n = 3) and -0.214 ± 0.033& (2SD, n = 12), respectively, for d109Ag. Moreover, we selected eight sphalerite samples from several hypogene deposits in China and obtained d109Ag values from -0.229& to 2.227&, indicating the significant Ag isotopic fractionation between Ag-bearing and Zn-rich minerals in hypogene deposits. In conclusion, this study shows the feasibility of accurately measuring Ag isotopes in Zn-rich samples and reveals their application potential in related Ag-bearing and Zn-rich deposits. [ABSTRACT FROM AUTHOR]

Due to the increasing demand for lead metal, the recovery of fine-grained galena resources is also constantly strengthening. High intensity conditioning (HIC) has been promoted as an efficient technology for enhancing the flotation of fine minerals. In this study, the effect of the HIC process with a multi-bladed impeller on the flotation of fine-grained galena was investigated at different agitation times and speeds. By analysis of flow field characteristics, adsorption experiments, and particle aggregation observation, the correlation mechanism of HIC affecting the flotation of fine-grained galena was revealed. Compared to the results without the HIC, the flotation recovery was 95.38% when the agitation speed was 2000 rpm and the agitation time was 5 min. Mechanistic studies showed that obtaining an appropriate slurry flow rate with external energy input not only benefited the dispersion of galena particles and reagents, but also enhanced their adsorption. The appropriate impeller shear stress can increase the flow rate difference of the slurry, making it easier for fine-grained galena to form clusters with appropriate particle size, compact structure, and small porosity, which promoted mineral flotation. This study will provide a basis for adjusting the floatability of fine sulfide mineral flotation from mixing operations. [ABSTRACT FROM AUTHOR]

Seafloor massive sulfides form in various marine hydrothermal settings, particularly within volcanic arcs, where magmatic fluids may contribute to the metal budget of the hydrothermal system. In this study, we focus on the Kolumbo volcano, a submarine volcanic edifice in the central Hellenic Volcanic Arc hosting an active hydrothermal system. Diffuse sulfate-sulfide chimneys form a Zn-Pb massive sulfide mineralization with elevated As, Ag, Au, Hg, Sb, and Tl contents. These elements have similar behavior during magmatic degassing and are common in arc-related hydrothermal systems. Trace-element data of igneous magnetite, combined with whole rock geochemistry and numerical modelling, highlights the behavior of chalcophile and siderophile elements during magmatic differentiation. We report that, despite early magmatic sulfide saturation, chalcophile element contents in the magma do not decrease until water saturation and degassing has occurred. The conservation of chalcophile elements in the magma during magmatic differentiation suggests that most of the magmatic sulfides do not fractionate. By contrast, upon degassing, As, Ag, Au, Cu, Hg, Sb, Sn, Pb, and Zn become depleted in the magma, likely partitioning into the volatile phase, either from the melt or during sulfide oxidation by volatiles. After degassing, the residual chalcophile elements in the melt are incorporated into magnetite. Trace-element data of magnetite enables identifying sulfide saturation during magmatic differentiation and discrimination between pre- and post-degassing magnetite. Our study highlights how magmatic degassing contributes to the metal budget in magmatic-hydrothermal systems that form seafloor massive sulfides and shows that igneous magnetite geochemistry is a powerful tool for tracking metal-mobilizing processes during magmatic differentiation. [ABSTRACT FROM AUTHOR]

The De'erni Cu–Zn-Co deposit is a typical altered ultramafic-hosted volcanogenic massive sulfide deposit comprising four lenticular main orebodies (0.57 Mt Cu, 1.27% Cu average ore grade; 0.03 Mt Co, 0.09% Co average ore grade; 0.16 Mt Zn, 1.04% Zn average ore grade) hosted in serpentinite and a 200-m-thick basalt was found below the No. I orebody. Serpentinite spinel Al2O3, TiO2, Cr#, and Mg# indicate a mantle-source. Serpentinite magmatic-hydrothermal genesis is indicated by the following: (i) high Rb/Y and Th/Zr ratios, low Nb/Zr ratios, and low δ65Cu values; (ii) altered magnetite rims on spinel being characterized by high Cr, Ni, and Ti, and low Ga contents; (iii) pyrite appears along the boundary of spinel grains and has a higher Co and Ni content than pyrite in ores. Therefore, the ultramafic host rocks are formed by strong fluid alteration of primary mantle rocks. The compositional zoning of Co, Cu, and Zn in euhedral coarse-grained pyrite from massive sulfide ore suggests that metal enrichment was associated with three fluid phases, with a clear temporal interval between the fluid activity that introduced Co/Cu enrichment and Zn enrichment (Zn-rich veins in magnetite cross-cut early spinel). Serpentinite exhibits a higher Zn content and decoupling of Ni and Co contents compared to Dur'ngoi ophiolite serpentinite distal from the orebody, implying primary ultramafic rocks may have provided Co to the ores. The apparently high Cu content of the Dur'ngoi ophiolite basalt in comparison with ophiolite basalts worldwide indicates basalt may have supplied the Cu. [ABSTRACT FROM AUTHOR]

Banchang is the largest Cu-Mo deposit (348 Mt @ 0.32% Cu and 428 Mt @ 0.07% Mo) in the Qinling orogenic belt, Central China. Orebodies are hosted in the contact between several granitoid dikes and graphite-bearing marble of the Neoproterozoic Yanlinggou Formation. Wallrock alteration comprises garnet skarn, pyroxene skarn, chlorite skarn, and stockwork chlorite-altered marble. Three hydrothermal stages are indicated: (I) prograde skarn stage, (II) retrograde skarn stage, and (III) main sulfides stage. New zircon U-Pb data show two magmatic events, including early Paleozoic granite porphyry (442 − 427 Ma), and late Mesozoic biotite monzogranite porphyry and late Mesozoic granite porphyry (147 − 146 Ma). The zircon trace element compositions show that the late Mesozoic granitoids with ∆FMQ = -0.7 to 2.3 (avg. 0.5; EuN/EuN* > 0.6) resemble the Cu ore-related granitoid in the Qinling orogenic belt and indicate high oxygen fugacity and water contents in the magma. The early Paleozoic granitoids have ∆FMQ= -2.4 to 0.6 (avg. -0.7; EuN/EuN* < 0.2). Electron Probe Microanalysis (EPMA) on the prograde garnet and pyroxene reveal predominantly andradite (And40 − 94Gro0−51) and diopside (Di53 − 98Hd10−55) compositions, respectively. The garnet Fe3+ contents decreases whereas the pyroxene Fe2+ contents increases from the late Mesozoic granitoid dikes to the marble. This suggests a gradual evolution of the skarn from an oxidized to a reduced state. Stage III sulfide minerals have δ34S = -2.1 to 4.8‰, indicating a magmatic origin. The temporal-spatial relationships, magmatic oxygen fugacity and water contents, zoning of prograde skarn minerals, and the source of sulfur indicate a genetic link between the skarn mineralization and late Mesozoic granitoid dikes. This study proposes a distal Cu-Mo skarn ore deposit model associated with granitoid dikes and some implications for mineral exploration in the Qinling orogenic belt and elsewhere. [ABSTRACT FROM AUTHOR]

Copper slag is a residue from the copper smelting process that not only takes up large amounts of space, but also contains harmful elements that can cause environmental pollution. In this paper, zinc in copper slag is sulfide-roasted using pyrite as a vulcanizing agent and anthracite and K2CO3 as additives, thus leaving zinc in the slag mainly in the form of ZnS. After sulfurization roasting, the slag can be stripped of Zn by flotation, and the remaining iron can be further applied in the blast furnace ironmaking process. The effects of temperature, holding time, pyrite addition, and K2CO3 addition on the Zn sulfation rate were investigated. The results showed that when pyrite, anthracite, and K2CO3 were added to the slag in amounts of 35, 2, and 10 pct of the slag's original mass, respectively, the total Zn in the slag was 3.16 pct, and its sulfuration rate was 83.5 pct. When pyrite was used to sulfide and dezincify copper bottom-blown smelting slag, the ZnO content in the slag was effectively reduced in preparation for subsequent ironmaking after flotation. This approach not only solves the problem of large piles of copper slag that cannot be fully utilized, but also alleviates the current shortage of iron ore in China. [ABSTRACT FROM AUTHOR]

The Xiling Gold Mine is a world-class giant monolithic gold deposit with an average gold content of 3.81 g/t, offering significant mining value. Utilizing techniques such as optical microscopy, scanning electron microscopy, and the mineral automatic analysis instrument(AMICS), the process mineralogical characteristics of the ore from the Xiling Gold Mine were analyzed, including an examination of mineral composition, dissemination grade, existence state of gold and its carrier minerals, and other pertinent features. The results indicate that gold in the ore primarily exists in the form of native gold and electrum. The majority of metal minerals are pyrite, accompanied by small quantities of sphalerite, chalcopyrite, galena, and arsenopyrite. Non-metallic minerals are predominantly quartz followed by muscovite, orthoclase, and potassium feldspar. Gold minerals within the ore mainly occurred in exposed gold form with a dissemination grain size concentrated above 10 µm. There is a close relationship between gold minerals and pyrite regarding their dissemination patterns; pyrite exhibits relatively coarse dissemination grain sizes, and the gold can be easily recovered under appropriate grinding fineness conditions at suitable reagent dosages during processing using full sulfide flotation technology. Based on the results of the process mineralogy analysis, the Xiling gold mine was processed using the full sulfide flotation process. The results of the closed -- circuit flow test show that under appropriate grinding fineness and reagent system conditions, the mineral processing indicators of Au 62.77 g/t with an Au recovery rate reaching 98. 89% can be achived. [ABSTRACT FROM AUTHOR]

A sulfur oxygen mixed copper ore in Laos has a copper grade of 1.23% and a copper oxidation rate of 26.02% with gold of 3.03 g/t, mostly existing in intergranular and encapsulated forms. The ore contains 10% bright gold, which can be pre-enriched by gravity separation. Copper sulfide minerals and other forms of gold minerals accounting for a large proportion are suitable for flotation. Adopting a combined heavy flotation process for comprehensive recovery of copper and gold, the loss of clear gold can be avoided, and the technical indicators obtained are: the gold grade of the re-selected concentrate is as high as 915.50 g/t, and the gold recovery rate is 12.09%. Under the optimal process parameters of using 1 000 g/t sodium sulfide and 500 g/t ammonium sulfate as activators with the collectors of 60 g/t pentyl xanthate and 60 g/t butyl ammonium black powder, the copper grade in the flotation concentrate reached 27.48%, the operating recovery rate was 91.38%, the gold grade was 59.25 g/t, and the operating recovery rate was 90.93%, which could achieve a comprehensive recovery of copper and gold. [ABSTRACT FROM AUTHOR]

Taking a complex and difficult-to-process iron ore from western Yunnan as the research object, X-ray fluorescence spectroscopy (XRF), chemical multi-element analysis, X-ray diffraction (XRD) and other methods were used to analyze the ore. The results show that the most valuable metal element in the ore is iron, which is mainly present in the form of magnetite. The sulfide minerals primarily include magnetite, pyrite and sphalerite, and the gangue minerals mainly include serpentine and talc. Based on the ore properties of the mine, a combined beneficiation process involving stage grinding and separation, magnetic separation, and flotation desulfurization was adopted to process the iron ore. By studying the effect of process parameters such as magnetic field strength, grinding fineness, types of activators, collectors and foaming agents on the quality improvement of iron ore by magnetic separation and flotation desulfurization, the optimal process parameters were obtained and closed-circuit tests were carried out according to the obtained best process conditions. Finally, a sulfur concentrate with an S grade of 21.90% and an S recovery rate of 68.52%, as well as an iron concentrate with a TFe grade of 61.56%, a TFe recovery rate of 67. 41%, and an S content of 0.67%, were obtained. The results could provide support for the efficient utilization of the iron ore resources. [ABSTRACT FROM AUTHOR]

We synthesized the solid solution between the sulfides CaS (oldhamite) and MgS (niningerite). Electron microprobe and X‐ray diffraction showed homogeneous and pure samples after the synthesis. The calculated lattice parameters fit to earlier literature data. Mid‐infrared spectroscopy of the samples reveal that the produced sulfides were fragile and tend to alternate very fast. However, we were able to provide clean reflectance spectra of all samples. The spectra of un‐altered samples show no peaks or bands but a rather constant spectrum within the analyzed spectral range between 7.0 and 12.5 μm. The altered spectra contain signatures of sulfates and carbonates and probably further compounds. The gathered data help to understand the formation conditions of the studies sulfides as it shows that the solvus exists in the CaS‐MgS system between 1000°C and 1200°C. In addition, the infrared data will help to improve remote sensing in the mid‐infrared of planetary objects that might be covered with sulfide containing material like asteroids or Mercury. Plain Language Summary: Oldhamite and niningerite are known to occur naturally in meteorites like aubrites. From that, some asteroids must partly consist of those minerals. In addition, Mercury is also known to consist of much sulfur and therefore suggested to have sulfides of the solid solution between oldhamite and niningerite on its surface. Investigating those minerals will therefore help to understand the formation conditions that lasted on those planetary objects. Hence, we were the first who produced the full solid solution of sulfide minerals between oldhamite (CaS) and niningerite (MgS). Those minerals can only form at very special conditions that we reconstruct in the laboratory because at normal conditions on Earth they are very unstable. We investigated the synthesized samples with X‐ray diffraction, electron microprobe analyzer, and infrared spectroscopy in the wavelength range between 7.0 and 12.5 μm, which is used for remote sensing. Our data confirmed earlier literature data in terms of lattice parameters and reveal that our experiments produced the sulfide samples correctly. Therefore, our data will help improve remote sensing of asteroids and potentially of planet Mercury. The gathered data are freely available at the IRIS infrared database. Key Points: Oldhamite is rapidly altered at the surface when exposed to air even under deliberately careful sample handling and dry air storageExpected flat spectra show bands of beginning alteration in the form of sulfites, sulfates and carbonatesSpectra of epoxy embedded samples show uniform spectra over the entire spectral range without bands [ABSTRACT FROM AUTHOR]

In view of the complex structure, difficult flotation and difficult leaching of low-grade mixed tungsten and molybdenum ore of a domestic company, the synergistic leaching of molybdenum and tungsten from molybdenum tungsten ore by hydrochloric acid pretreatment--pyrolusite + sulf uric acid was studied. The effects of various factors on the leaching rate of tungsten and molybdenum were investigated. The results show that under the conditions of hydrochloric acid concentration of 1.5 mol/L, liquid volume to solid mass ratio of 6.5/1 and atmospheric pressure, the tungsten and molybdenum ores are pretreated with hydrochloric acid. Under the optimal conditions of filter slag of 20 g, particle size of 200 mesh, pyrolusite dosage of 4 g, sulfuric acid of 8 mol/L, liquid volume to solid mass ratio of 5/1, temperature of 90 °C and leaching time of 3 h, the leaching rates of molybdenum and tungsten are 83% and 73%, respectively. [ABSTRACT FROM AUTHOR]

P204 was used to extract copper and cobalt from low concentration cobalt sulphide concentrate leaching solution. The effects of pH of extraction solution, extractor concentration, extraction ratio and time on the extraction efficiency were investigated. The results show that under the conditions of pH = 4, P204 volume fraction of 25 %, extraction ratio VO/VA = 1/1, extraction time of 3 min, reverse extractant sulfuric acid concentration of 0.10 mol/L, and reverse extraction ratio VO/VA = 2/1, the test of two-stage countercurrent extraction, four-stage countercurrent stripping is carried out on the purified liquid of cobalt sulfide concentrate, the mass concentration of cobalt and copper in the raffinate is 338.80 mg/L and 2.96 mg/L, the extraction rate of copper is 98.32%, and 90.03% of cobalt remains in the water phase. Copper and cobalt can be effectively further separated by stripping, which is conducive to preparation of high purity cobalt sulfate. [ABSTRACT FROM AUTHOR]

Manganese dioxide in pyrolusite was directly reduced to manganese sulfate by high-temperature roasting with ammonium sulfite as reducing agent, so as to achieve efficient extraction of pyrolusite. The effects of mass ratio of ammonium sulfite to pyrolusite, roasting temperature and time, leaching temperature and time on the extraction rate of manganese were investigated, and the optimum process conditions were determined. The results show that the optimal conditions are the mass ratio of ammonium sulfite to pyrolusite of 0.75:1, roasting temperature of 500 °C, roasting time of 1.5 h, leaching temperature of 25 °C, leaching time of 30 min. Under the conditions, the leaching rate of manganese and iron is about 93% and about 9.5%, respectively. The extraction effect of manganese is good. [ABSTRACT FROM AUTHOR]

The generation of acid mine drainage (AMD) characterized by high acidity and elevated levels of toxic metals primarily results from the oxidation and dissolution of sulfide minerals facilitated by microbial catalysis. Although there has been significant research on microbial diversity and community composition in AMD, as well as the relationship between microbes and heavy metals, there remains a gap in understanding the microbial community structure in uranium-enriched AMD sites. In this paper, water samples with varying levels of uranium pollution were collected from an abandoned stone coal mine in Jiangxi Province, China during summer and winter, respectively. Geochemical and high-throughput sequencing analyses were conducted to characterize spatiotemporal variations in bacterial diversity and community composition along pollution groups. The results indicated that uranium was predominantly concentrated in the AMD of new pits with strong acid production capacity, reaching a peak concentration of 9,370 µg/L. This was accompanied by elevated acidity and concentrations of iron and total phosphorus, which were identified as significant drivers shaping the composition of bacterial communities, rather than fluctuations in seasonal conditions. In an extremely polluted environment (pH < 3), bacterial diversity was lowest, with a predominant presence of acidophilic iron-oxidizing bacteria (such as Ferrovum), and a portion of acidophilic heterotrophic bacteria synergistically coexisting. As pollution levels decreased, the microbial community gradually evolved to cohabitation of various pH-neutral heterotrophic species, ultimately reverting back to background level. The pH was the dominant factor determining biogeochemical release of uranium in AMD. Acidophilic and uranium-tolerant bacteria, including Ferrovum, Leptospirillum, Acidiphilium, and Metallibacterium, were identified as playing key roles in this process through mechanisms such as enhancing acid production rate and facilitating organic matter biodegradation. [ABSTRACT FROM AUTHOR]

Pyrite is a ubiquitous sulfide mineral found in diverse geological settings and holds great significance in the formation of Au deposits as well as the safe utilization of groundwater due to its remarkable ability to incorporate substantial amounts of As. However, despite its importance, there remains a dearth of fundamental data on the partitioning of As between pyrite and fluid, which is key for accurately modeling the As distribution in these environments. Here, we present new insights into the partitioning behavior of As between pyrite and fluid at conditions that mimic natural fluid systems. Pyrite was synthesized by replacement of natural siderite in hydrothermal experiments at 200 °C and pH 5 applying a wide range of fluid As concentrations, spanning from 0.001 to 100 µg/g. The As distribution and concentration in synthetic pyrite was analyzed by quantitative LA-ICP-MS mapping providing a high spatial resolution and sensitivity at 2–3 µm image pixel size at a detection limit of ∼1 µg/g at the single pixel scale. Pyrite-fluid partitioning coefficients (D As (py/fluid)) between synthetic pyrite and experimental fluid agree with previously published data for high fluid As concentrations of 1 µg/g to 100 µg/g (D As < 2000). However, at low As concentrations in the experimental fluid (<1 µg/g), a steep increase in the D As (py/fluid) values of up to ∼30,000 was detected, demonstrating even stronger As partitioning into pyrite. This is confirmed by the analyses of natural pyrite that precipitated from As-poor fluids (0.3–0.4 ng/g) within a deep anoxic aquifer in SE Sweden. The discovery holds significant implications for the mobility and scavenging of As, which in turn is important for understanding the formation and fingerprinting of mineral deposits as well as for the secure utilization of groundwater resources. [ABSTRACT FROM AUTHOR]

The Kochbulak gold deposit is situated on the northern slope of the Kurama range of eastern Uzbekistan and is one of the largest Tellurium-rich epithermal gold deposits in the world. Based on a detailed field and petrological investigation, three stages of mineralization can be classified, including, from early to late, quartz–pyrite vein stage, quartz–telluride–sulfide–sulphosalt–native gold stage, and pyrite–chalcopyrite vein stage. Abundant tellurides, including tellurobismuthite, rucklidgeite, tetradymite, altaite, volynskite, and hessite, have been well recognized in the second (main) mineralization stage. Based on the mineral assemblages and petrogenetic occurrence, the sequence of tellurides in the second mineralization stage can be approximately identified as altaite+calaverite+native tellurium, calaverite+native gold, Bi-telluride (e.g., tellurobismuthite and rucklidgeite)+petzite+native gold, Ag-Bi telluride (e.g., volynskite), and Ag-telluride (e.g., hessite)+native gold. By depicting the Log ƒ(Te2)-Log ƒ(S2) relationship diagram of the Kochbulak gold deposit under 250 °C and 200 °C, the Log ƒ(S2) value ranges from −14.7 to −8.6 and from −16.7 to −10.9, respectively, with Log ƒ(Te2) value varies from −12.3 to −7.8 under 250 °C and ranges from −13.8 to −11.2 under 200 °C. [ABSTRACT FROM AUTHOR]

In recent years, there have been important breakthroughs in the exploration for sandstone-hosted uranium (U) deposits in the Louzhuangzi district of the southern Junggar Basin. Between 2020 and 2023, a medium-sized sandstone-hosted uranium deposit production area was identified in the region. Only a few investigations have been conducted at the Louzhuangzi U deposit, including those analyzing its geological–tectonic evolution, basic geological features, hydrogeology, and ore-controlling factors. It is generally believed that uranium mineralization at the Louzhuangzi U deposit is controlled by a redox zone. Organic matter (referred to as OM hereafter) consisting of bitumen and carbonaceous debris is very common in the uranium ores (especially in high-grade ores) at the Louzhuangzi U deposit. However, the characteristics of the OM and its contribution to uranium's mineralization have not been studied in detail. In this study, OM-rich U-ores, altered sandstone, and barren sandstone samples were collected for petrography, mineralogical, micro-spectroscopy, carbon, and sulfur isotope studies. The results of this study show that the distribution of U minerals and metal sulfides (pyrite, sphalerite, etc.) was strictly controlled by bitumen at the Louzhuangzi U deposit. The bitumen may have been formed by hydrocarbon-rich and U-rich ore-forming fluids, which were formed after hydrocarbon generation and expulsion in the underlying Jurassic coal-bearing source rocks. The fluids contained U, Zn, Fe, and other metal elements, which migrated together and then precipitated into the oxidized Toutunhe Formation sandstone through cracking and differentiation processes. Therefore, the results indicate that migrated hydrocarbons were involved in U mineralization, in addition to oxidation–reduction processes, in the Louzhuangzi district, south of the Junggar Basin (China). [ABSTRACT FROM AUTHOR]

Prospecting efforts to located Au mineralization within the Altai-Sayan fold area (ASFA) over previous decades have revealed that Devonian epithermal Au-Ag mineralization is more widespread than previously recognized. The preservation of this type of mineralization in Paleozoic rocks offers new prospects for the exploration of Au-Ag deposits in the underexplored region of Gornaya Shoria. The Kalarskoe epithermal Au-Ag occurrence represents Devonian epithermal mineralization within the Kaburchak cluster, Gornaya Shoria, Russia. This occurrence is confined to zones of argillic alteration that were superimposed on previously formed propylites. The argillic-altered rocks host quartz-sulfide veinlet zones. The mineralization of the Kalarskoe site is characterized by a high abundance of sulfide minerals: commonly, 5%–10%; often, up to 20%; and in some cases, up to 60%–70%. The ore minerals are represented by pyrite, arsenopyrite, sphalerite, galena, chalcopyrite, fahlores, native Au, and electrum, as well as by the sulfosalts Pb, Bi, Ag, Cu, and the tellurides of Au, Ag, and Pb. Based on mineralogical observations, at least four generations of sulfide mineral formations are distinguished within the ore occurrence. The mineralization of the Kalarskoe ore occurrence may be assigned to the intermediate sulfidation (IS) type. The results of the (U,Th)-He dating of pyrite from the pyrite-arsenopyrite massive body (pyr-3 and 4) revealed the protracted history of the mineralization in the intervals from ~399 to ~371 Ma. The obtained results substantially enhance the prospecting models for the exploration of epithermal Au-Ag deposits in the western part of the Altai-Sayan fold area (ASFA). [ABSTRACT FROM AUTHOR]

The Lianzigou deposit, which has an Au–Te paragenetic association, is hosted in plagioclase gneiss of the Qincanggou Formation in the Taihua Group in the Xiaoqinling region, central China. This quartz vein-type Au deposit comprises native Au and a variety of tellurides. The latter include calaverite (AuTe2), krennerite (Au3AgTe8), petzite (Au3AgTe2), hessite (Ag2Te), melonite (NiTe2), and altaite (PbTe). Four stages have been recognized in this deposit: stage I consists of K-feldspar and quartz; stage II is of milky quartz veins accompanied by coarse-grained disseminated and lumps of pyrite with weak Au mineralization; stage III is composed mainly of Au, tellurides, and sulfides; and stage IV is characterized by abundant carbonate and quartz. Based on mineral assemblage and thermodynamic data, we estimated the physicochemical conditions of the main metallogenic stages. Based on thermodynamic modelling, the physicochemical conditions of Au–Ag–Te mineral associations were estimated. The Au–Ag–Te minerals from stage III formed mainly under conditions of logƒO2 = −43.15 to −33.31, logƒH2S = ~−9.29, pH < 7, logfTe2 = −10.6 to −9.8 and logαAu+/αAg+ = −7.2 to −6.5. In contrast, the physicochemical conditions of stage II were higher, specifically pH (8.3–8.5) and logƒO2 (−34.90−31.96). In the ore-forming fluids of the Lianzigou deposit, the dominant Au species was Au(HS)2− while the dominant Te species were HTe−(aq) and Te22−(aq). Moreover, the Au–Ag–Te metal associations in the Lianzigou Au deposit were derived from mantle materials related to lithospheric thinning of the eastern North China craton in the Early Cretaceous under an extensional tectonic system. [ABSTRACT FROM AUTHOR]

Iran hosts more than 350 Precambrian to Cenozoic sediment-hosted Zn-Pb±Ba and barite-sulfide deposits, including shale-hosted massive sulfide (SHMS, also called SEDEX) and Irish-type and Mississippi Valley-type (MVT) mineralization, and barite is a common mineral in these deposits. In the SHMS deposits, barite is typically found as fine-grained disseminations in thin laminae. In these deposits, the sulfide laminae often occur as diagenetic replacements and as bands containing authigenic and diagenetic barite and pyrite framboids. In the Irish-type Zn-Pb-Ba and stratabound barite-sulfide deposits, barite exhibits various textures, including fine-grained disseminated barite, banded zebra textures, veins, and massive barite lenses. In some of the giant Irish-type deposits, as well as in the stratabound barite-sulfide mineralization, the main stratabound sulfide ore is developed within a barite envelope and is characterized by the replacement of barite and pyrite by chalcopyrite, galena, and sphalerite. In the MVT deposits, the formation of barite is often related to dolomitization, and sulfide mineralization involves the replacement of the dolomitized carbonate rocks, as well as associated barite. Fluid inclusion studies on the Irish-type deposits indicate that the temperatures and salinities of the sulfide-forming fluids are higher compared to those of the barite-forming fluids. Fluid inclusion analyses of coarse-grained barites from Irish and MVT deposits reveal their hydrothermal origin. The δ3⁴S values of sulfide minerals (pyrite, sphalerite, and galena) in Irish-type deposits exhibit a broad range of low values (mostly −28 to +5‰), primarily revealing a process of bacterial sulfate reduction (BSR). However, the textures (replacement, colloform, and banded) and more positive sulfur isotope values (+1 to +36‰) in the SHMS Zn-Pb deposits suggest that bacterial sulfate reduction (BSR) plays a less significant role. We suggest that thermochemical sulfate reduction (TSR) connected to the direct replacement of barite plays a more relevant role in providing sulfur for the sulfide mineralization in the SHMS, barite-sulfide, and MVT deposits. Based on the textual evidence, sulfur isotopic data, and fluid inclusion studies, barite has been identified as a key controller for the subsequent Zn-Pb mineralization by providing a suitable host and significant sulfur contribution in the sediment-hosted Zn-Pb and stratabound barite-sulfide deposits. This implies that diagenetic barite might be a precursor to all types of sediment-hosted Zn-Pb mineralization. [ABSTRACT FROM AUTHOR]

Water recycling in mining is essential to decrease water usage, which results in the accumulation of high concentrations of inorganic and organic substances in the process water. Consequently, adverse impacts on the flotation process of copper sulfides may arise. High-molecular-weight polymers based on anionic polyacrylamides (PAMs) are used as tailing flocculants in mineral processing plants. The recirculation of water recovered from the tailing thickeners to the flotation process introduces residual PAMs, which can impact the flotation of important copper sulfides like chalcopyrite, bornite, and enargite. This issue has been rarely studied. In this work, results on the effect of an anionic polyacrylamide (PAM) of medium–low anionicity on the flotation of chalcopyrite, enargite, and bornite are reported and analyzed. The results show that PAM molecules depress the flotation of chalcopyrite, enargite, and bornite under a wide range of pH values. The experimental data indicate that the depressing effect of PAMs on copper sulfides increases with pH. The zeta potential results reveal that this parameter becomes less negative with the addition of PAMs, indicating interactions between PAM molecules and the surfaces of the copper sulfides. PAM adsorption on copper sulfides increases with pH, which correlates with the flotation and zeta potential data. It is proposed that the interactions between PAM molecules and copper sulfides are explained by the presence of surface iron and copper hydroxides that create chemically active adsorption sites. [ABSTRACT FROM AUTHOR]

This document is an editorial for a special issue on "Valuable Metals Recovery by Mineral Processing and Hydrometallurgy." It emphasizes the importance of metals for society and the need for efficient techniques to process ores and extract metals. The recovery of metals from secondary sources, such as mining waste, is also highlighted. The editorial discusses various aspects and challenges of metal recovery, including the use of flotation in mineral beneficiation and the application of hydrometallurgical methods. It presents studies on grinding media, pulp oxidation-reduction potential, and the use of new reagents for metal recovery. The editorial also explores the extraction of metals from refractory ores and mining waste. Overall, the papers in this special issue demonstrate the potential for recovering valuable metals from various sources using modern techniques and theoretical frameworks. [Extracted from the article]

In South China, karst groundwater is an important water resource for industrial, agricultural, and drinking purposes. However, karst aquifers are highly vulnerable to pollution, leading to deteriorating karst groundwater quality and posing potential health risks to local residents. In this study, 22 groundwater samples were collected from a karst aquifer in the southwestern part of Hubei Province. The hydrogeochemical characteristics and their controlling factors were examined, and the potential health risks associated with groundwater pollutant concentrations in karst groundwater were assessed. The results showed that the groundwater is slightly alkaline with low chemical oxygen demand values, indicating good water quality. The groundwater facies type was identified as HCO3‐Ca at most sample spots, showing low total dissolved solids concentrations. Substantial spatial variations in Na+, CO32−, and NO2− concentrations were found, whereas spatial variations in the K+, Ca2+, Cl−, HCO3−, and F− concentrations were small. In addition, the dissolution of gypsum deposits and magnesium carbonate sedimentary rocks at sampling sites resulted in groundwater facies types of HCO3•SO4‐Ca and HCO3‐Ca•Mg, with low total dissolved solids concentrations. The karst groundwater chemistry in the study area was mainly controlled by water–rock interactions, as well as by the dissolution of gypsum deposits and magnesium carbonate sedimentary rocks at specific groundwater sampling sites. The groundwater Cl− concentrations were mainly affected by atmospheric precipitation. NO3− was mainly derived from atmospheric precipitation, domestic sewage, septic tanks, and industrial activities, whereas SO42− was derived from atmospheric precipitation, sulfate rock dissolution, and sulfide mineral oxidation. These results highlight the absence of potential human health risks of NO3− and F− to infants, children, and adults, as their concentrations are below the corresponding regional background values. In contrast, the potential health risks of Cl− cannot be ignored, particularly for infants. This study offers scientific guidelines for protecting and allocating local groundwater resources. Practitioner Points: The dissolution of gypsum deposits and magnesium carbonate sedimentary rocks resulted in groundwater facies types of HCO3 + SO4‐Ca and HCO3‐Ca·Mg.The karst groundwater chemistry in the study area was mainly controlled by water–rock interaction.The groundwater Cl− concentrations were mainly affected by atmospheric precipitation.The potential health risks of Cl− were not negligible, particularly for infants. [ABSTRACT FROM AUTHOR]

Multispectral remote sensing data provided valuable information for hydrothermal minerals exploration. In this article, Landsat-8 Operational Land Imager (OLI) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were processed and analyzed using band ratio and principal component techniques to demarcate areas of hydrothermal mineral resources by highlighting the most influenced zone of hydrothermal alteration (high-grade) in Egypt. The area is a part of the Arabian-Nubian Shield, covering 1068 km2, and comprises wide varieties of Pre- and Pan-African rock assemblages. Preparing and integrating thematic layers consisting of the grade of hydrothermal intensity in a GIS technique supported generating a hydrothermal mineral predictive map (HMPM) using a multi-criteria decision-making technique. The plausible zone of very high mineral resources covers about 6.57 %. Analysis of ASTER data revealed that this zone is reliable with phyllic and argillic minerals and iron-oxides. The results of OLI data helped in demarcating potential areas of hydrothermal alteration areas (Al–OH) mixed with iron oxides. Field observations and investigations enabled the validation of the HMPM. The spatial distribution of hydrothermal zones throughout the study was reliable to that observed in the mine areas. Field and ore microscopic examination verified the existence of Au-sulfide minerals connected with hydrothermal alteration zones (HAZs) in different areas e.g., Abu-Marawat, Gidami, Semna, AbuGaharish, and Hamama mines. Overall, integrating multi-spectral data through overlay analysis techniques can provide valuable information about hydrothermal mineral resources in an accurate and cost-effective approach. [ABSTRACT FROM AUTHOR]

Deep‐marine brine seeps in the modern ocean are considered analogs for settings that favored the formation of sedimentary‐exhalative zinc and lead deposits in deep time. Microbial activity plays an important role in the accumulation of ore minerals, meaning that the extent of mineralization is at least indirectly dependent on nutrient fluxes. Here, we investigated the biogeochemical nitrogen cycle in shallow (15–50 cm) sediment cores from the Orca Basin brine pool and surrounding sites, as well as from an active brine seep area near Dead Crab Lake in the Gulf of Mexico, with the aim of constraining the effect of brine seepage on this bio‐essential element. We find high porewater ammonium concentrations in the millimolar range, paired with elevated ratios of organic carbon to nitrogen in sediments, which confirm previous hypotheses that the brine recycles ammonium from sedimentary strata back into the water column. Within Orca Basin, we note tentative evidence of microbial ammonium utilization. At the active seep, ammonium is mixed into the overlying water column and likely undergoes oxidation. Isotopic data from sediments and dissolved ammonium, paired with previously published genomic data, suggest the presence of dissimilatory nitrate reduction to ammonium at the brine‐seawater interface. We conclude that brine seeps can stimulate biological nitrogen metabolisms in multiple ways. Our results may help calibrate studies of biogeochemical cycles around brine seeps that are archived in the rock record. Plain Language Summary: Brine seeps in the deep ocean are sites where fluids with exceptionally high salinity, up to 10 times that of seawater, seep up through marine sediments and are dispersed into the water column. Such saline fluids can carry high concentrations of metals such as iron, zinc, lead and copper, and therefore brine seeps have been proposed as mechanisms for the formation of ore deposits in the past. An important aspect in this theory is that high microbial activity of primary and secondary producers near the brine seeps creates locally anoxic conditions under which metals are trapped in sulfide minerals. Such biological activity would require input of nutrients, including nitrogen. To shed more light on the biogeochemical nitrogen cycle in brine seeps, we investigated nitrogen isotopes and abundances in samples from the Gulf of Mexico. Here, ammonium concentrations in the millimolar range have previously been documented. Our results support the idea that nitrogen is leached by the brines from deeper sediments and released into the overlying water column. Furthermore, we find evidence for specific microbial metabolisms that are stimulated by mixing between anoxic brine fluids and oxygenated seawater, which may also have occurred in past ore‐forming environments. Key Points: Brine seeps in the Gulf of Mexico recycle bioavailable nitrogen from sediments back into the water columnNitrogen isotopes suggest that brine seepage stimulates biological activity, including dissimilatory nitrate reduction to ammoniumBiological productivity stimulated by brine seeps may have contributed to the formation of sedimentary ore deposits [ABSTRACT FROM AUTHOR]

Gold mineralisation in Goz-Beida within the southern Ouaddai massif in eastern Chad is hosted by quartz veins oriented NW-SE to NE-SW in Abilelaï and ENE-WSW to NE-SW in Kalaka. Quartz in the veins from both sites is brecciated with foliated wall-rock selvages and cut across Neoproterozoic metasedimentary rock. Alteration minerals include quartz, pyrite, chalcopyrite, galena, covellite, telluride, hematite, magnetite, sericite and chlorite, with the quartz and pyrite assemblage closely associated with gold mineralisation. The phases of hydrothermal alteration include silicification, sulphidation, ferruginisation, sericitisation and chloritisation. Parameters that consistently define alteration in the wall-rock include silicification, sulphidation, carbonitisation and K-feldspar alterations. Paragenetic and micro-structural characterisation of the vein minerals reveals that the gold-bearing veins might have been emplaced during brittle/ductile deformation events within a shear zones. The gold grains are alloyed with Ag. Gold grains that occur as inclusions in pyrite from Abilelaï show fineness values that vary between 438 and 860 and are characterised by inclusions of galena and telluride. The occurrence of galena as inclusions in gold and pyrite reflects a hydrothermal quartz vein sulphide system possibly related to a fluid system with inputs from the granitoids in the area. Free gold grains from Kalaka show fineness values that range from 903 to 922. The primary Ag content of the gold is typical of granitoid-related vein systems. Such high fineness values can be attributed to sulphidation as the dominant mechanism for ore deposition. Electron microprobe analysis on sulphide phases in the vein and wall-rock in Abilelaï depicts a Au-Ag-Pb assemblage. Analysis on sulphides and telluride phases in quartz veins from Kalaka reveals a characteristic Au-Ag-Pb-Te assemblage. Thus, brecciated stockwork sulphide and telluride-bearing veins and the wall-rock within an arc setting in prospective mining sites are the main target for gold in Goz- Beida. [ABSTRACT FROM AUTHOR]

Paleoproterozoic (2.05 Ga) komatiites are widespread in the Central Lapland Greenstone Belt (CLGB), northern Finland. Close association with sulfur (S)-rich country rocks and spatiotemporal connection with the Cu-Ni(-PGE) deposits of Kevitsa and Sakatti make these komatiites interesting targets for sulfide deposit exploration. We provide whole-rock geochemical data from Sattasvaara komatiites and combine it with literature data to form a geochemical database for the CLGB komatiites. We construct a model for the komatiites from adiabatic melting of the mantle source to fractional crystallization at crustal conditions. Using MELTS, we calculate three parental melts (MgO = 20.6–25.7 wt%) in equilibrium with Fo92, Fo93, and Fo94 olivine for the CLGB komatiites. Based on REEBOX PRO simulations, these parental melts can form from a single mantle source by different pressures and degrees of melting when the potential temperature is 1575–1700 °C. We calculate ranges of S contents for the parental melts based on the different mantle melting conditions and degrees of melting. We use Magma Chamber Simulator to fractionally crystallize the parental melt at crustal conditions. These simulations reproduce the major element oxide, Ni, Cu, and S contents from our komatiite database. Simulated Ni contents in olivine are compatible with literature data from Kevitsa and Sakatti, hence providing a baseline to identify Ni-depleted olivine in CLGB komatiites and related intrusive rocks. We show that fractional crystallization of the komatiitic parental melt can form either Ni-rich or Cu-rich sulfide melt, depending on the initial Ni and S content of the parental melt. [ABSTRACT FROM AUTHOR]

This study explored, on a laboratory scale, how matte separates from the gangue in the black top of a PGM smelter. Two PGM concentrates, one with high sulfide content (17.3 mass%, Platreef concentrate) and the other with low sulfide content (1.3 mass%, UG-2 concentrate), were studied in the temperature range of 800°C to 1480°C, which is the temperature gradient across the black top. The results showed that effective matte separation occurs at temperatures when the matte is completely molten, and a substantial amount of liquid silicate phase has formed. The main matte separation mechanism is the coalescence of sulfide prills and their gravitational settling through the continuous path created by the liquid silicate phase. Complete matte separation occurs at lower temperatures in Platreef concentrate (1400°C in Platreef concentrate vs. 1480°C in UG-2 concentrate), due to the higher concentration of liquid silicate phase of lower viscosity, as well as the higher amount of sulfide minerals in this concentrate. PGMs already dissolve and collect in a nickel-iron-based alloy associated with the matte at temperatures as low as 900°C. [ABSTRACT FROM AUTHOR]

For decades, there has been debate surrounding the transport of dense metal-rich sulfide liquid in mafic magmas. This topic is crucial to understanding the genesis of valuable resources of nickel, copper, and platinum-group elements, which are essential for a sustainable, emission-free energy future. Recent studies of mineralized mafic magmas suggested that gas bubbles adhere to sulfide globules, reducing their density and favoring upward transport. While this hypothesis may explain sulfide mobility in near-surface magmatic environments, it is at odds with key mineralogic and textural observations and does not explain how long-distance sulfide transport operates. Here, we suggest an alternative hypothesis that builds on previous observations, focusing on the interaction between carbonate melt and sulfide liquid. We demonstrate experimentally that carbonate melt wraps sulfide globules forming a relatively mobile pair that may mediate metal-rich sulfide transport from mantle to crust. [ABSTRACT FROM AUTHOR]

Special attention was drawn to the heavy metals contained in coal, due to it will cause harm to the environment during coal processing and utilization. The sequential chemical extraction of Shanxi coal (SX coal) and Wulanchabu coal (WLCB coal) was carried out to investigate the distribution of arsenic (As) in coals. Two raw coals were pyrolyzed at 300–900 °C in horizontal tubular furnace to investigate release behavior of As during pyrolysis process. The results showed that As in SX coal mainly existed in aluminosilicate-bound state (40.25%) and disulfide-bound state (32.51%), followed by carbonate-bound state and organic-bound state. The As in WLCB coal mainly existed in aluminosilicate-bound state (62.50%), followed by disulfide-bound state (19.10%). The As contents of water-soluble, ion-exchange and residue states in the two coals were less than others. The modes of occurrence of As had great influence on its volatilization behavior. As in organic part was easy to volatilize at low temperature. Sulfide-bound state would escape with the decomposition of pyrite. Because SX coal contained higher organic state and sulfide-bound state, the volatilization rate of As was higher than WLCB coal at any temperature, and the difference was more obvious at low temperature. In addition, FactSage simulation value was basically consistent with the experimental value. [ABSTRACT FROM AUTHOR]

Clay minerals have different negative effects on the froth flotation process such as low adsorption of collectors on valuable minerals, increased pulp viscosity, and the reduction in recovery and grade concentrates of copper sulfides. This study aims to evaluate the use of polystyrene-based nanoparticles (NPs) for the froth flotation of chalcopyrite and their ability to mitigate the negative effect of montmorillonite on the recovery of this sulfide. The experimental stage consisted of preparing a type of polystyrene-based nanoparticle (St-CTAB-VI), which was analyzed by dynamic night scattering (DLS) to establish its hydrodynamic size. Then, the effect of NPs on chalcopyrite's angle's in the presence and absence of montmorillonite (15%) was evaluated and compared with the contact angle achieved using potassium amyl xanthate (PAX) and a mixture of PAX and NPs. In addition, zeta potential measurements were carried out to investigate the interactions between the chalcopyrite and the montmorillonite or the NPs under fixed concentrations and microflotation tests were performed employing different times to evaluate the chalcopyrite recovery in the presence of montmorillonite, using NPs and mixtures with PAX. Finally, turbidity analysis as a function of time was performed to evaluate the occurrence of sedimentation and flocculation phenomena in suspensions of 15% montmorillonite in the presence and absence of chalcopyrite, nanoparticles, and mixtures of NPs and PAX. The results indicated that the mixture of NPs and PAX contributed to increasing the contact angle of chalcopyrite in the presence of montmorillonite. This can be associated with the presence of molecular and nanometric collectors that generated a higher hydrophobicity on the chalcopyrite particles, contributing to reducing the presence of clay minerals on the mineral surface. In addition, the mixture of NPs and PAX promoted the generation of nanoparticles on the sulfide mineral surface, which helps to detach the slime and facilitate the bubble/mineral attachment step during flotation. [ABSTRACT FROM AUTHOR]

Iron and sulfur-oxidizing microorganisms play important roles in several natural and industrial processes. Leptospirillum (L.) ferriphilum, is an iron-oxidizing microorganism with a remarkable adaptability to thrive in extreme acidic environments, including heap bioleaching processes, acid mine drainage (AMD) and natural acidic water. A strain of L. ferriphilum (IESL25) was isolated from an industrial bioleaching process in northern Chile. This strain was challenged to grow at increasing concentrations of sulfate in order to assess changes in protein expression profiles, cells shape and to determine potential compatible solute molecules. The results unveiled changes in three proteins: succinyl CoA (SCoA) synthetase, isocitrate dehydrogenase (IDH) and aspartate semialdehyde dehydrogenase (ASD); which were notably overexpressed when the strain grew at elevated concentrations of sulfate. ASD plays a pivotal role in the synthesis of the compatible solute ectoine, which was identified along with hydroxyectoine by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF). The relationship between IDH, SCoA, and ectoine production could be due to the TCA cycle, in which both enzymes produce metabolites that can be utilized as precursors or intermediates in the biosynthesis of ectoine. In addition, distinct filamentous cellular morphology in L. ferriphilum IESL25 was observed when growing under sulfate stress conditions. This study highlights a new insight into the possible cellular responses of L. ferriphilum under the presence of high sulfate levels, commonly found in bioleaching of sulfide minerals or AMD environments. [ABSTRACT FROM AUTHOR]