Search

In this study, pyrite flotation in seawater in the presence of Cu2+and Pb2+ and the underlying mechanisms were investigated systematically. Flotation results indicated that Cu2+ and Pb2+ increased pyrite recovery from 52.51% to 79.45% and 72.57% in weak alkaline seawater (pH 8) due to the increased surface hydrophobicity. Solution species distribution and electrochemical studies cross-confirmed that the Cu2S and Pb(OH)2 layer formed on the pyrite surface at pH 8, subsequently increasing the adsorption sites of xanthate on the pyrite surface. Differently, the pyrite flotation remained at a lower recovery of around 20% than that with the addition of 10−7–10−5 M Cu2+ and Pb2+ in strong alkaline seawater (pH 10). No activation species were adsorbed on the pyrite surface at pH 10 due to the coverage of hydrophilic precipitation on the pyrite surface, resulting in a poor floatability. This study therefore provides scientific guidelines for pyrite separation in seawater in the presence of Cu2+ and Pb2+. [ABSTRACT FROM AUTHOR]

The Huxu Au-dominated polymetallic deposit is a hydrothermal deposit located in the Dongxiang volcanic basin in the middle section of the Gan-Hang tectonic belt in South China. The orebodies primarily occur within the Jurassic-Cretaceous quartz diorite porphyry, while the genesis of this deposit is unclear. This study focused on geological and mineralogical characteristics, in-situ trace elements and S-Pb isotopes of three generations of pyrite of the Huxu deposit to clarify the distribution of trace elements in pyrite, ore-forming fluid and material sources, and genetic types of the deposit. The mineralization stage of the deposit can be divided into quartz-pyrite stage (S1), quartz-pyrite-hematite stage (S2), quartz-polymetallic sulfide stage (S3) and quartz-hematite stage (S4), with the corresponding pyrite being divided into three generations (Py1–Py3). in-situ trace element data of pyrite show that Au in pyrite mainly exists in the form of solid solution (Au+), and the content is relatively low at all stages (0.18 ppm for Py1, 0.32 ppm for Py2, 0.68 ppm for Py3), while Pb and Zn mainly exist as sulfide inclusions in the pyrite. S-Pb isotopes show that the sulfur and ore-forming material of this deposit are mainly sourced from magma. The mineral association, mineral textures and trace elements in different stages of pyrite indicate that fluid boiling and fluid mixing are the key factors of native gold precipitation in S2 and S4, respectively, while water-rock interaction controlled the precipitation of Pb-Zn sulfides. These integrating with geological characteristics suggests that the deposit should be an intermediate sulfidation epithermal deposit. [ABSTRACT FROM AUTHOR]

The article presents the results of studies of composite magnesium oxychloride iron-containing binders. The research is aimed at solving the problem of increasing operational durability and expanding the scope of application of magnesium materials. The purpose of the work is to study hydrate formation, hardening, and properties of composite magnesium binders with varying contents of iron compounds. Compositions of caustic magnesite (magnesium oxide) with iron oxides, with ferruginous minerals (andradite and pyrite), and with waste from the enrichment of magnetite ores have been studied. The scientific novelty of the research results lies in the identification of patterns of hydration of magnesium oxychloride binder with a high content (at least 50%) of iron compounds. The mutual influence of magnesium and ferruginous components during hydration and formation of the binder structure has been established. Schemes for the formation of hydrates involving andradite and pyrite have been proposed. The qualitative composition of the main hydrates of composite binders was determined by diffractometric and differential thermal analysis methods. The microstructure of the materials was studied by electron microscopy. The structure of magnesium paste made from a composite binder is formed by crystals of magnesium pentahydroxychloride and amorphous gel-like iron-containing hydrates. In composite binders containing iron oxide or andradite, magnesium hydroxychlorocarbonate is formed. The dependence of the stability of magnesium hydroxychlorocarbonate on the content of magnesium oxide and chloride was revealed. The patterns of the influence of iron compounds on the hydration and hardening of magnesium oxide form the basis for the development of a composite binder containing 50%–70% magnetite ore enrichment waste. A composite binder containing a ferrous man-made component is not inferior in strength properties to caustic magnesite and is characterized by high structural resistance to long-term operational impacts. [ABSTRACT FROM AUTHOR]

Enhanced recoveries of gold-bearing minerals, namely pyrite, chalcopyrite and arsenopyrite, are essential to meet the ever-increasing demand for the precious metal. Since flotation is the 1st step in the recovery of these minerals, a detailed understanding of their surface structure as well as the interaction of the collector molecules with these surfaces is essential to not only rationalize experimental observations but also design new task specific collector molecules. In the present work, we have employed density functional theory (DFT) simulations to understand the surface characteristics of pyrite, arsenopyrite and chalcopyrite and to evaluate the adsorption of a commonly used collector, 2-mercaptobenzothazole (MBT), on these surfaces. DFT calculations reveal that (001) and (100) surfaces of chalcopyrite undergo significant reconstruction, while (110) and (112) surfaces of chalcopyrite, (100) surface of pyrite and (001), (100), (011), (110) and (111) surfaces of arsenopyrite undergo only atomic relaxations. MBT (both the thione and thiol tautomers) chemisorbs on all the three minerals, with the adsorption strength varying in the following order: pyrite > arsenopyrite > chalcopyrite. A stronger adsorption of MBT on pyrite over chalcopyrite explains the experimentally observed selectivity of MBT for the former. Furthermore, results from these simulations provide detailed atomic scale insights into the bonding mechanisms at the surfaces, that are crucial for a rational design of novel flotation collectors with enhanced efficiencies. [ABSTRACT FROM AUTHOR]

Pyrite (FeS2), as a transition metal sulfide, has a promise application in the field of secondary batteries due to its abundant reserves, high theoretical capacity, safety, and non‐toxicity. However, serious volume expansion and shuttle effect of FeS2 in liquid secondary batteries limit its further development. Solid‐state batteries offer effective solutions to these challenges. In this review, the synthesis methods of FeS2 and recent progress in FeS2‐based solid‐state lithium/sodium batteries are presented, and the effects of FeS2 size and morphology, solid electrolyte type, and battery structure design on the electrochemical performance of solid‐state batteries are discussed. By analyzing and summarizing the problems in applying FeS2 in solid‐state batteries, the remaining challenges in this field are discussed and future directions are proposed. This review aims to guide research on high‐performance solid‐state batteries based on FeS2 and promote further development of FeS2 in electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Porphyry-type molybdenum (copper) deposits have long been a focus of geological studies. 770 Molybdenum(Copper) Deposit, a newly discovered porphyry-type deposit in the Northern Greater Khingan Mountains, has seen limited reporting. This study examines pyrite and chalcopyrite within 770 Molybdenum (Copper) Deposit using electron microscopy and EPMA(Electron Probe Micro-analysis) to investigate the crystal morphology and the major and trace element compositions of these sulfides, providing a comprehensive understanding of their chemical characteristics and geological significance. The 770 Molybdenum (Copper) Deposit, a large porphyry-type molybdenum (copper) deposit, has its ore bodies hosted in Late Jurassic granite porphyry. Alteration zones are divided into a central potassic zone and a peripheral pyrite-sericite zone. EPMA results show pyrite with sulfur content generally below 53. 45 %, iron content below 46. 55 %, and a w(S)/w(Fe) ratio≥1. 148, indicating that the deposit-s pyrite is low-iron, low-sulfur pyrite, formed under conditions of high sulfur fugacity. The trace-to-major element correlations suggest elements like Zn, Mo, Ni, Co, and As exist in pyrite as mineral inclusions. The w(Co)/w(Ni) ratio(2. 25-4. 50) in pyrite indicates a magmatic-hydrothermal origin, while the [n(Cu)＋n(Fe)]/n(S) ratio in chalcopyrite(average 0. 91) suggests formation in a mid to low-temperature(around 200 ℃) hydrothermal environment. [ABSTRACT FROM AUTHOR]

Qinglonggou Gold Deposit is a significant gold deposit in Tanjianshan Goldfield, northern margin of Qaidam. The ore bodies are mainly hosted in Mesoproterozoic carbon-bearing dolomitic marble of the Wandonggou Group, with some found in intrusive diorite porphyrite. However, the diorite porphyrite’s chronology, source, origin of gold-bearing materials, and gold content variation have not been adequately addressed, limiting the understanding of mineralization and the potential for further exploration. Zircon U-Pb geochronology and sulfur isotopes and trace elements in pyrite from gold-bearing diorite porphyrite were analyzed using LA ICP MS. The findings reveal that the diorite porphyrite formed in the Early Permian (293. 0 Ma±1. 8 Ma), with zircon εHf(t) values ranging from -3. 5 to 4. 8 and a two-stage model age (TDM2) between 912 and 1375 Ma, indicating material from the Mesoproterozoic middle-lower crust with mantle contributions. Pyrite in the diorite porphyrite exhibits low δ34S values, low Au content, high As content, and elevated w(Co)/w(Ni) ratios (δ34S=4.01 ‰-4. 58 ‰; w(Au)=0. 10×10-6-0. 49 ×10-6, averaging 0. 26×10-6; w(As)=404.61×10-6-9 546.27×10-6, averaging 5 779. 62×10-6; w(Co)/w(Ni)=3. 86-97. 37), differing significantly from the δ34S, Au content, As content, and w(Co)/w(Ni) values of pyrite in the carbon-bearing dolomitic marble host rock (δ34S=8.4 ‰-15.8 ‰, w(Au)=1.92×10-6-30. 28×10-6, w(As)=9 029. 20×10-6-130 727. 48×10-6, w(Co)/w(Ni)=0.11-0.38). This suggests that gold mineralization likely originated from deep-seated Early Permian magma or mantle degassing. The low gold content in pyrite suggests a limited contribution to mineralization, with exploration efforts focusing primarily on gold bodies within carbon-bearing dolomitic marble, followed by magmatic rocks. [ABSTRACT FROM AUTHOR]

Pyrite is one of the most abundant metal sulfide tailings and is susceptible to oxidation, yielding acidic mine drainage (AMD) that poses significant environmental risks. Consequently, the exploration of pyrite surface oxidation and the kinetic influencing factors remains a pivotal research area. Despite the oxidation of pyrite producing a significant amount of sulfate (SO42−), a comprehensive investigation into its influence on the oxidation process is lacking. Leveraging pyrite's semiconducting nature and the electrochemical intricacies of its surface oxidation, this study employs electrochemical techniques—cyclic voltammetry (CV), Tafel polarization, and electrochemical impedance spectroscopy (EIS)—to assess the effect of SO42⁻ on pyrite surface oxidation. The CV curve shows that SO42− does not change the fundamental surface oxidation mechanism of pyrite, but its redox peak current density decreases with the increase in SO42−, and the surface oxidation rate of pyrite decreases. The possible reason is attributed to SO42− adsorption onto pyrite surfaces, blocking active sites and impeding the oxidation process. Furthermore, Tafel polarization curves indicate an augmentation in polarization resistance with elevated SO42− concentrations, signifying heightened difficulty in pyrite surface reactions. EIS analysis underscores an increase in Weber diffusion resistance with increasing SO42⁻, indicating that the diffusion of Fe3+ to the pyrite surface and the diffusion of oxidized products to the solution becomes more difficult. These findings will improve our understanding of the influence of SO42− on pyrite oxidation and have important implications for deepening the understanding of surface oxidation of pyrite in the natural environment. [ABSTRACT FROM AUTHOR]

The high sulfur content in North-East Indian coal is one of the primary challenges with using it as an energy source. Therefore, the present study uses Burkholderia sp. GR 8-02 to explore coal beneficiation from the Tipong mine (T20 and T60) in Assam (North-East India). Various particle size fractions (−125 to +210 µm, −210 to +250 µm, −250 to +297 µm, −297 to +400 µm and −400 to +500 µm) were treated and subjected to petrographic and chemical analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS), Thermogravimetric analysis (TGA), and Raman spectral analysis. The results revealed a 39.04% and 32.43% reduction in total sulfur for T20 and T60 samples, respectively. The ash content decreased by 19.79% in the T20 coal sample and by 24.52% in the T60 coal samples, with a relative decrease in the mineral matter content of approximately 17.43%. Following beneficiation with Burkholderia sp. GR 8-02, the −125 to +250 µm coal fraction exhibited maximum ash removal. The T20 sample useful heating value increased from 8116 to 8203 kcal/kg and the T60 sample from 8060 to 8210 kcal/kg. X-ray diffraction and FTIR patterns showed mineral phases like quartz, kaolinite, and pyrite. The FTIR spectra indicated altered C-S, SO2, and C=O bonds. The thermal profile showed a 12.54% mass loss difference between untreated and treated coal samples, suggesting lower thermal stability post-treatment without affecting the useful heating value (UHV). The treated coal's surface leaching and morphological structure changes were investigated using Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS) images. Raman analysis revealed increased carbon crystallinity and molecular structure in treated coal. This study offers an environmentally friendly and efficient approach to clean coal production. [ABSTRACT FROM AUTHOR]

This study describes the first, use of eco-friendly welan gum as a new depressant in galena-pyrite flotation separation. The depression mechanism were examined using micro-flotation and various characterization techniques. The selective depression performance of welan gum on pyrite was found to effectively enhance the galena/pyrite flotation separation index. Compared with the addition of NaBX alone, the grade of Pb in the produced concentrate increased by more than 28% (from 40.86% to 70.02%). And it was possible to recover 87.79% of galena and only 15.98% of pyrite. There was an accentuated increase in the electronegativity of the pyrite surface by more than ~ 8 mV after treatment with welan gum alone compared to an increase of ~ 1 mV for galena, which can be explained by the fact that welan gum selectively adsorbed on the pyrite surface in significant amounts. As a result, the subsequent adsorption of xanthate is prevented. This finding has been further proven by adsorption measurement results. The X-ray photoelectron spectroscopy and Time-of-Flight secondary ion mass spectrometry results indicated that the hydroxyl groups in welan gum showed acid – base interactions with the metal hydroxylated species anchored on the mineral surfaces, which may be the main driving force in the adsorption process. Differences in the amount of metal hydroxide on the mineral surface, as well as the electrical affinity of metal ions in metal hydroxide, contributed to the selective adsorption of welan gum. Therefore, welan gum can be regarded as a potential pyrite-depressant. [ABSTRACT FROM AUTHOR]

In the field of mineral processing, the efficient separation of stibnite and pyrite has always been a technical challenge. In a gold-antimony mixed flotation concentrate, gold is mainly encapsulated in pyrite, and the valuable metallic mineral are mainly encapsulated and pyrite. In order to address this mixed concentrate, a new process of sulfuric acid pretreatment followed by flotation separation was adopted for experimental research. The results showed that when the gold grade in the mixed concentrate was 66.28 g/t and the antimony grade was 12.94%, sulfuric acid was used for desliming pretreatment. Under the action of residual reagents, a highly efficient inhibitor called YTJ was added. After one roughing and one scavenging flotation separation operation, a high-antimony gold concentrate with antimony grade of 34.10%, gold content of 70.20 g/t, gold recovery of 36. 65% and antimony recovery of 90.08% was obtained. A low-antimony gold concentrate with gold grade of 64.20 g/t, antimony content of 1.74%, and gold recovery of 63.35% was also achieved. These results provide a new approach for the efficient separation of gold-antimony bulk flotation concentrates. [ABSTRACT FROM AUTHOR]

The research of this paper was carried out on the low-temperature (100 ± 2 °C) pressure (0.2–0.8 MPa) leaching of pyrite, chalcopyrite and their mixture. According to experiments on chalcopyrite dissolution, increasing the oxygen pressure from 0.2 up to 0.8 MPa had a slight effect on chalcopyrite dissolution. Oxygen pressure and initial sulfuric acid concentration in the range of 10–50 g/L had the greatest positive effect on the pyrite oxidation. The SEM and EDX mappings indicate the chalcopyrite and pyrite surfaces to be passivated by elemental sulfur. The oxidation degree of pyrite in its mixture with chalcopyrite increased significantly from 54.5 up to 80.3% in 0–240 min. The reaction time is relative to the dissolution of the individual mineral, while the dissolution of chalcopyrite remained virtually unchanged. The addition of Cu (II) and Fe (III) ions does not influence pyrite dissolution when chalcopyrite is added in a leaching process, which can be explained by the formation of an electrochemical link between the minerals. The positive effect of chalcopyrite addition is associated with a decreased formation of elemental sulfur on the surface of pyrite. The described method can be used for the hydrometallurgical processing of copper raw materials with increased pyrite content, as well as for the pretreatment of copper concentrates with gold-rich pyrite concentrates to increase the recovery of gold and silver. [ABSTRACT FROM AUTHOR]

Experimental investigation of the fractionation behavior of Cu isotopes during the replacement of pyrite by Cu-bearing sulfides (chalcopyrite, bornite, and chalcocite) was conducted under hydrothermal conditions. At the initial stages of the replacement reaction, small mounds of product formed on the pyrite surface; these mounds then grew and coalesced, progressively covering the pyrite grains as the reaction proceeded. Chalcopyrite, bornite, and chalcocite formed sequential monomineralic zones from the pyrite reaction front towards the solution. During the early stage of the reaction, Cu isotope fractionation between the solids and the aqueous solution (Δ65Cu solid-aqueous , Δ65Cu solid-aqueous = δ65Cu solid – δ65Cu aqueous) was approximately –0.6 ‰, similar to the calculated equilibrium Cu isotope fractionation factors between Cu-bearing sulfides (chalcopyrite, bornite, and chalcocite) and CuCl 2 –. However, the Δ65Cu solid-aqueous moved progressively further from equilibrium with prolonged reaction time, with fractionation factors ranging from approximately –0.6 ‰ to –1.2 ‰. We found that significant fractionation of Cu isotopes between the solid products and aqueous solution was mainly controlled by the amount of chalcopyrite that formed in the product layers. We interpret that the Δ65Cu solid-aqueous was controlled by the diffusion of aqueous Cu(I) species among the product layers and the changes in Cu redox state during the precipitation of chalcopyrite. These results imply that the δ65Cu values measured in sulfides from low-temperature hydrothermal deposits may be controlled by the local chemistry of the fluids in product layers that precipitate sulfides. This study highlights the importance of local fluid characteristics, such as redox conditions, metal speciation, and diffusion, in controlling isotope fractionation pathways during non-equilibrium mineral replacement. [ABSTRACT FROM AUTHOR]

Various green materials like biochar and Fe0 (nano-scale zerovalent iron, nZVI) have been applied to remediate aqueous Cr(VI) contamination, but few studies have tried to further improve the performance of nZVI and/or biochar composites with different sulfidation methods. Here, we modified a hybrid material of nZVI@biochar with Na2S and pyrite (FeS2), applied it to remove aqueous Cr(VI) under different experimental conditions, and revealed key factors influencing Cr(VI) removal performance. The results show that pyrite loading is an effective sulfidation method to increase the Fe and S contents in composites. FeSx-nZVI@BC (1:1) had a Cr(VI) removal efficiency of ~95% with 5 mg/L Cr(VI) loaded, which was much higher than other hybrid composites. The Cr(VI) removal efficiency of FeSx-nZVI@BC showed a decreasing trend under pH conditions that increased from pH 3 to pH 9. The presence of dissolved oxygen and aqueous Cu2+ and Cd2+ could significantly suppress the removal of aqueous Cr(VI), while humic acids at different concentrations did not suppress Cr(VI) removal. After the reaction, it was observed with an energy-dispersive spectrometer (SEM-EDS) that most Cr in the solid phase was closely associated with pyrite minerals. X-ray photoelectron spectroscopy (XPS) spectra, together with the Fe2+-quenching method, confirmed that Fe (Fe2+ or Fe0) acted as the main electron donor, contributing to ~90% of the Cr(VI) reduction. Our study indicates that pyrite loading could further improve the performance of remediation materials and that the pyrite-loaded nZVI@BC composite is a green material with strong potential to be applied in the remediation of water contaminated by Cr(VI). [ABSTRACT FROM AUTHOR]

Pyrite has natural floatability and thus readily enters valuable mineral flotation concentrates, diluting their quality and decreasing their economic value. Its separation is challenging, depending on process conditions, the presence of activating ions, and water quality, particularly in regions where seawater is used. This study examines the effect of various doses of sodium metabisulfite (SMBS) on pyrite depression in freshwater and seawater under weakly alkaline conditions and with different copper ion concentrations. Without the addition of activators or depressants, pyrite recovery is 40% in freshwater and 60% in seawater, whereas with 10 ppm of SMBS, recoveries drop to 28% and 38%, respectively. The addition of 10 ppm Cu2+ increases recovery by 10% in freshwater and by 20% in seawater. In the presence of 75 ppm of PAX, maximum recovery reached 50% in freshwater and 80% in seawater. These results suggest that cationic bridges formed by seawater ions, combined with CaOH+ activation, play a critical role in pyrite activation, even in the presence of depressants. [ABSTRACT FROM AUTHOR]

In this work, a series of electrical conductivities of pyrite-bearing dacite were measured under 10−1–106 Hz, 573–973 K, 1.0–3.0 GPa, and different pyrite contents ranging from 0 vol.% to 20 vol.%) using a Solartron–1260 A impedance analyzer. For the dacite sample with 5 vol.% pyrite, the electrical conductivity of the dacite increased with temperature but slightly decreased when the pressure was increased from 1.0 GPa to 3.0 GPa. In the temperature range of 573–973 K, the bulk electrical conductivity of the pyrite-bearing dacite gradually increased with increasing pyrite percentage from 0 vol.% to 20 vol.% at 1.0 GPa. Thus, a positive correlation between the electrical conductivity of the sample and the pyrite content was typically observed. In light of the significant enhancement in the electrical conductivity of the interconnected pyrite in the dacite, the value of the percolation threshold was determined as 7 vol.%. Furthermore, the dominant conduction mechanism of the small polaron for pyrite-bearing dacite was proposed from our obtained results on the chemical compositions and activation enthalpies under high-temperature and high-pressure conditions. A comprehensive consideration of our constructed electrical conductivity–depth profile based on the electrical conductivity of the pyrite-bearing dacite, can provide a good constraint on the volume of pyrite in dacite for high-conductivity Duobaoshan island arc. In conclusion, the presence of pyrite in dacite can provide a reasonable explanation for the high-conductivity anomaly observed in the region of Duobaoshan island arc. [ABSTRACT FROM AUTHOR]

The Sanhetun tellurium–gold (Te–Au) deposit, located in the Duobaoshan polymetallic metallogenic belt (DPMB) within the eastern section of the Central Asian Orogenic Belt (CAOB), is a newly discovered small-scale gold deposit. The mineralization, with a resource of ≥4 t Au, is mainly hosted in three NNE-trending alteration zones between Early Carboniferous granitic mylonite and Lower Cretaceous volcanogenic-sedimentary formations. The genesis of formation of this deposit is poorly constrained. Here, we report the results of petrographic studies, TESCAN Integrated Mineral Analyzer (TIMA), major and trace element concentrations, and in situ S isotopes of pyrite. The results show that there are four types of pyrite: coarse-grained euhedral Py1, fine-grained quartz-Py2 vein crosscutting Py1, anhedral aggregated Py3, and anhedral aggregated Py4. The pre-ore stage Py1 contains negligible Au, Te, and other trace elements and has a relatively narrow range of δ34S values ranging from −1.20 to −0.57‰. Py2 has higher concentrations of Au and Te and distinctly high concentrations of Mo, Sb, Zn, and Mn with markedly positive δ34S values of 4.67 to 14.43‰. The main-ore stage Py3 contains high Au and Te concentrations and shows narrow δ34S values ranging from −5.69 to 0.19‰. The post-ore stage Py4 displays low Au concentrations with the δ34S values ranging from 2.66 to 3.86‰. Tellurides are widespread in Py3 and Py4, consisting mainly of native tellurium, tetradymite, tsumoite, hessite, and petzite. Especially, tetradymite commonly coexists with native gold. This study highlights the role of Te–Bi–S melt as an important gold scavenger in As-deficient ore-forming fluids. [ABSTRACT FROM AUTHOR]

Mitigating acid mine drainage (AMD) at its source, specifically within rocks containing pyrite in underwater environments, poses a significant environmental challenge worldwide. Existing passivation techniques are primarily designed for open-air conditions, involving direct contact with coating materials at a solid–liquid interface, making them ineffective beneath a water barrier. In this study, we introduce a novel passivation method inspired by the design of underwater bio-adhesives. Tannic acid (TA) combined with polyethylene glycol (PEG) was employed to form a hydrophobic film directly on the pyrite surface, overcoming water resistance and addressing the limitations of current techniques. Electrochemical experiments and chemical leaching experiments were conducted to evaluate the oxidation resistance of the passivating films. TA–PEG-coated pyrite exhibited a lower oxidation rate and a higher static contact angle of 126.2°, achieving suppression efficiencies of 71.6% for total Fe release and 68.1% for total S release. A comprehensive characterization approach, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), was employed to investigate the passivation mechanism. The results of this study may provide new insights into the preparation of simpler and greener passivating agents to suppress pyrite oxidation at its source in underwater environments. [ABSTRACT FROM AUTHOR]

The clean and efficient utilization of coal is a promising way to achieve carbon neutrality. Coking coal is a scarce resource and an important raw material in the steel industry. However, the presence of pyrite sulfur affects its clean utilization. Nonetheless, this pyrite could be removed using depressants during flotation. Commonly used organic depressants (sodium lignosulfonate (SL), calcium lignosulfonate (CL), and pyrogallol (PY)) and inorganic depressants (calcium oxide (CaO) and calcium hypochlorite (Ca(ClO)2)) were chosen in this study. Their inhibition mechanism was discussed using FTIR, XPS, and molecular dynamics (MD) methods. The desulfurization ability of organic depressants was shown to be better than inorganic ones. Among the organic depressants, PY proved to be advantageous in terms of low dosage. Physical adsorption was identified as the main interaction form of SL, CL, and PY onto the surface of pyrite, as evidenced from FTIR and XPS analyses. Similarly, MD simulation results showed that hydrogen bonds played a proactive role in the interactions between PY and pyrite. The diffusion coefficient of water molecules on the pyrite surface was also observed to decrease when organic depressants were present, indicating an increase in the hydrophilicity of pyrite. This research is of great significance to utilize sulfur-containing coal and minerals. [ABSTRACT FROM AUTHOR]

During pyrite mining, tailings and waste residues are generated, and the oxidation of exposed metal sulfides leads to significant environmental issues such as acid mine drainage pollution. Studying the oxidation mechanism of pyrite is crucial for inhibiting or preventing the formation of acid mine drainage. Alkaline amino acids were used as electrolytes to explore the electrochemical oxidation mechanism of pyrite. Through electrochemical methods such as OCP, CV, Tafel polarization curve, LSV, and EIS, the electrochemical behavior of pyrite surfaces was measured, confirming the feasibility of pyrite oxidation in an alkaline amino acid system. The oxidation mechanisms of pyrite were consistent across the 3 alkaline amino acids, with the oxidation rate of pyrite following the order: lysine>arginine>histidine. [ABSTRACT FROM AUTHOR]

Yongxin Gold Deposit is located in the southern part of Duobaoshan Cu-Mo-Au metallogenic belt. To understand the genesis of the deposit and provide exploration insights, a study was conducted on the rare earth elements, micro-elements, and isotopic composition of gold-bearing pyrite. The results indicate that the chemical composition of pyrite shows enrichment in light REEs and depletion in heavy REEs, with a right-sloping REE distribution pattern. The pyrite is enriched in high-field-strength elements such as U, Th, Zr, and Hf, and depleted in large-ion lithophile elements like Ba and Sr. Ratios such as w(Hf)/w(Sm), w(Nb)/w(La), and w(Th)/w(La) suggest that the ore-forming fluid contained more Cl than F. A negative Eu anomaly and the absence of a Ce anomaly indicate that the ore-forming fluid formed under reducing conditions. Ratios like w(Y)/w(Ho), w(Zr)/w(Hf), and w(Nb)/w(Ta) suggest that the mineralization process did not involve external hydrothermal fluids, nor did metasomatism occur, with the ore-forming fluid closely related to both mantle and crustal sources. The sulfur isotopic characteristics indicate that the ore-forming materials originated from deeper sources. Genetic indicators such as w(Co)/w(Ni) and w(Fe)/w(S＋As) suggest that the deposit is of a meso-epithermal volcanic hydrothermal origin. Based on the magmatic origin, tectonic setting, diagenesis-mineralization age, metallogenic process, geochemical characteristics, and the main features of representative gold deposits in the region, it is concluded that Yongxin Gold Deposit belongs to a porphyry metallogenic system, forming during the Early Cretaceous as a meso-epithermal, relatively Cl-rich, weakly reducing gold deposit. [ABSTRACT FROM AUTHOR]

Cobalt is a critical and strategic metal mainly found as associated element in several types of deposits, of which skarn‐type deposits are the major sources. Han‐Xing type skarn iron deposit, having high grade iron ore and associated cobalt, is a typical skarn‐type iron ore in China. But the complete recovery and exploitation of cobalt are restricted because of the lower grade of related cobalt and the dearth of prior research on its occurrence condition and enrichment mechanism. In this paper, pyrite from five typical ore deposits in the Han‐Xing area was studied by using electron probe microanalysis (EPMA) and laser‐ablation inductively‐coupled‐plasma mass‐spectrometry (LA–ICP–MS) techniques to decipher the occurrence state and enrichment mechanism of associated cobalt in skarn‐type iron deposits. The results show that Co2+ replaces Fe2+ in pyrite through isomorphism. The distribution of cobalt in pyrite from different deposits varies greatly, that is, in the Xishimen iron deposit, the cobalt content is comparatively enriched in the pyrite's core. In contrast, in other deposits, the cobalt content is concentrated in the pyrite's rims, where it can be up to 1000 times higher than in the core. The cobalt mineralization in Han‐Xing area can be divided into several stages. The sulphur element of sulphide is mainly derived from evaporite, while cobalt mineralization occurred in the early stage with pyrite formation or in the late stage by metasomatism/cementation of Co‐rich ore‐forming fluid. The magma assimilated with the Ordovician evaporite not only promoted iron mineralization, but also became the main controlling factor for cobalt enrichment. [ABSTRACT FROM AUTHOR]

With the continuous development of mineral resources to high altitude areas, the study of sulfide ore flotation in unconventional systems has been emphasized. There is a consensus that moderate oxidation of sulfide ore is beneficial to flotation, but the specific suitable dissolved oxygen value is inconclusive, and there are few studies on sulfide ore flotation under low dissolved oxygen environment at high altitude. In this paper, we designed and assembled an atmosphere simulation flotation equipment to simulate the flotation of pyrite at high altitude by controlling the partial pressure of N2/O2 and dissolved oxygen under atmospheric conditions. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), Fourier transform infrared spectrometer (FT-IR), UV-vis spectrophotometer, zeta potential, and contact angle measurements were used to reveal the effects of surface oxidation and agent adsorption on pyrite at high altitude (4600 m dissolved oxygen (DO) = 4.0 mg/L). The results of pure mineral flotation indicated that the high altitude and low dissolved oxygen environment is favorable for pyrite flotation. Contact angle measurements and XPS analysis showed that the high altitude atmosphere slows down the oxidation of pyrite surface, facilitates Sn2−/S0 production and enhances surface hydrophobicity. Electrochemical calculations and zeta potential analysis showed that the influence of atmosphere on the form of pyrite adsorption is small, and the different atmospheric conditions are consistent with dixanthogen electrochemical adsorption, with lower Zeta potential under high altitude atmosphere and significant potential shift after sodium isobutyl xanthate (SIBX) adsorption. The results of FT-IR, UV-vis, and AFM analysis showed that SIBX adsorbed more on the surface of pyrite under high altitude atmosphere and adsorbed on the surface in a mesh structure composed of column/block. The results of the experimental study revealed the reasons for the easy flotation of sulfide ores at high altitude with less collector dosage, and confirmed that the combined DO–pH regulation is beneficial to achieve more efficient flotation of pyrite. [ABSTRACT FROM AUTHOR]

Porphyry-epithermal veins hosting Re-rich molybdenite and rheniite (ReS2) from the Maronia Cu-Mo ± Re ± Au porphyry in Thrace, NE Greece, provide new insights into the hydrothermal processes causing extreme Re enrichment. Quartz trace element chemistry (Al/Ti, Ge/Ti), Ti-in-quartz thermometry, and cathodoluminescence imaging reveal multiple quartz generations in consecutive hydrothermal quartz-sulfide veins associated with potassic, sericitic, and argillic alteration. Fluid inclusions in different quartz generations indicate that phase separation and fluid cooling are the main ore-forming processes in the porphyry stage (~ 500 – 350 °C), whereas mixing of a vapor-rich fluid with metalliferous (e.g., Pb, Zn, Au) meteoric water forms the epithermal veins (~ 280 °C). These processes are recorded by trace element ratios in pyrite that are sensitive to changes in fluid temperature (Se/Te), fluid salinity (As/Sb, Co/As), and mixing between fluids of magmatic and meteoric origin (Se/Ge). Highly variable intra-grain δ34S values in pyrite record S isotope fractionation during SO2 disproportionation and phase separation, emphasizing the importance of in situ δ34S analysis to unravel ore-forming processes. High δ34S (~ 4.5‰) values of sulfides are indicative of low SO42−/H2S fluid ratios buffered by the local host rocks and mixing of the magma-derived fluid with meteoric water. The formation of Re-rich molybdenite (~ 6600 ppm) is favored by cooling and reduction of a magma-derived, high-temperature (~400 °C), oxidized, and Re-rich fluid triggering efficient Re precipitation in early veins in the potassic alteration zone. The systematic temporal fluid evolution therefore reveals that coeval cooling and reduction of oxidized Re-rich fluids cause extreme Re enrichment at the Maronia porphyry system. [ABSTRACT FROM AUTHOR]

Coal is often adhered to by pyrite during slime flotation, causing an increase in the sulfur content of clean coal. In order to study the mechanism of pyrite adhesion to coal surfaces, different coal structural units were built and optimized, and the most stable adsorption model of them on pyrite surfaces was determined. The mechanism of pyrite particles adhering to the surface of coal slurries was explored with the method of DFT. The results showed that the interaction mechanism between pyrite surface and Ph-OH and Ph-O-CH3 was the result of a weak interaction between the H atom of Ph-OH and Ph-O-CH3 and the S atom of the pyrite surface. The interaction mechanism between the pyrite surface and Ph-COOH and Ph-CO-CH3 was both as a result of H-S interactions and weak Fe-O interactions. On the whole, there were weak interactions between pyrite particles and the coal slurry, and the pyrite particles can spontaneously adsorb on the surface of the coal slurry. [ABSTRACT FROM AUTHOR]

To control acid mine drainage (AMD) from the source, a new environmentally and green passivator (biochar) has been introduced to passivate pyrite. To reduce the difficulty of biochar preparation and cost, and improve its production scale, in-situ pyrolysis of applewood by smoldering to produce biochar. Here, particle size, moisture content and gas flow rate were selected to prepare biochar by smoldering through orthogonal combination, and the pyrite was passivated with different conditions and biochar concentrations (2 g/L, 3 g/L, 4 g/L). The results revealed that when the particle size is 200 mm×200 mm×20 mm, the water content is 20–30%, and the gas flow rate is 0.4 L/m3, the biochar yield is the highest. Biochar promotes the formation of passivating layer (jarosite), inhibits the release of metal ions. Increasing biochar concentration can promote the formation of jarosite and enhance the passivation effect on pyrite. [ABSTRACT FROM AUTHOR]

Abstract Flotation is the most common method for effective separation of pyrite and carbonate minerals from Carlin-type gold deposits. The effect of conventional xanthate collector on flotation of a Carlin-type gold mine in Guizhou province is poor, and it can not effectively remove carbonate minerals. In this paper, butyl xanthoxanthate and benzohydroxamic acid (BHA) were used as a new combined collector for the flotation separation of a Carlintype gold mine in Guizhou Province. The flotation behavior of pyrite and its adsorption mechanism on pyrite surface were discussed in detail through pure mineral flotation test, actual ore flotation test, contact Angle test, infrared spectrum analysis and XPS analysis. The results showed that the collection capacity of butyl xanthoxime combined with benzohydroxamic acid was obviously stronger than that of BHA or butyl xanthoxime alone. The optimal ratio of pyrite flotation with combined collector is 3, and the recovery rate of pyrite flotation is 37%, which is higher than that of pyrite flotation recovery of 30.5% when benzohydroxamic acid is used alone and 28.5% when butyl xanthate is used alone. The contact Angle test, infrared spectrum and XPS analysis showed that the combined collector of butyl xanthate and benzohydroxamic acid (BHA) produced strong chemical adsorption on the surface of pyrite. Bha can increase the adsorption capacity of butyl xanthate on the surface of pyrite, which is conducive to the flotation recovery of pyrite.

One of the most important methods in the beneficiation of sulfide ores is flotation. Flotation experiments on a laboratory scale are mainly carried out through batch flotation and microflotation tests. In this study, comparative flotation experiments of pyrite minerals were conducted under the same conditions using the two methods mentioned above. A series of experiments were carried out with different pH values and collector dosages selected as flotation parameters. The highest flotation recovery was obtained at a pH of 7.5 with the use of PAX. Furthermore, within the conditions studied, a correlation of 94% was found between the two flotation techniques when using PAX, while it was 98% in the use of PEX. In this study. It was shown that the microflotation method can be used to estimate the efficiency values that can be obtained with batch flotation experiments.

Gold grains are observed in a variety of forms, such as coarse-liberated native gold grains, and ultra-fine grains associated with sulfide or non-sulfide mineral particles, in the form of solid solution in sulfide minerals, mainly pyrite. In the flotation of gold ores, bulk sulfide mineral flotation is generally applied to maximize gold recovery. This approach gives high gold recoveries, but it also causes the recovery of barren sulfide minerals (i.e., sulfide mineral particles with no gold content), which increases concentrate tonnage and transportation costs and reduces the grade sometimes to below the saleable limit (approx. 10 g/t Au). This study addresses the differences between gold-bearing and barren pyrite particles taken from various ore deposits and utilizes these differences for the selective flotation of gold-bearing pyrite. The laboratory scale flotation tests conducted on three pyrite samples having different cyanide soluble gold contents show that a selective separation between gold-bearing pyrite and barren pyrite particles could be achieved under specific flotation conditions. Gold recovery is correlated directly with the cyanide-soluble gold in the ore samples. Electrochemical experiments were conducted to elucidate the differences in surface properties of the two types of pyrite. The barren pyrite particles were more cathodic and prone to cathodic reduction of OH− and depressant ions on the surface, and they could be depressed effectively without significantly affecting the gold-bearing particles. [ABSTRACT FROM AUTHOR]

A microfine-grained complex refractory gold ore in Henan has a grade of 1.2 g/t, but the recovery rate by beneficiation is low. To improve the recovery rate and economic benefits, a process mineralogy study was conducted on the flotation tailings. The study revealed that the gold-bearing minerals in the tailings are primarily pyrite, followed by silicate minerals such as quartz and feldspar. The pyrite particles are mostly smaller than 0.038 mm, typically occurring as fine particles intergrown with gangue minerals or encapsulated within them, with occasional monomeric occurrences. The monomer liberation degree is only 4. 60%, indicating that increasing the grinding fineness could further recover the gold from the tailings. Open-circuit and closed-circuit tests showed that when the grinding fineness was increased to 0.074 mm accounting for about 85%, and the flotation reagent regime was optimized and adjusted, the recovery rate increased to 85.86%, leading to significant economic benefits. [ABSTRACT FROM AUTHOR]

Previous studies have indicated that acid-washed pyrite is inert toward aqueous U(VI) under most pH conditions at ambient temperature, even though insoluble UO 2 is the thermodynamically predicted product for the reduction of U(VI) by pyrite. Considering the exothermic nature of nuclear waste, the interaction between uranyl nitrate/acetate and natural pyrite was studied at temperatures ranging from 25 °C to 85 °C and at pH values between ∼4.0 and ∼9.5, to simulate the scenarios encountered in a high-level radioactive waste repository. The results revealed that the reactivity of pyrite toward aqueous U(VI) significantly increased with rising temperature, and the reaction could be described by a pseudo-first-order kinetic equation. Activation energies were calculated to be 79.4 ± 10.6 and 45.7 ± 3.8 kJ⋅mol−1 for the reduction of uranyl nitrate, and 78.2 ± 5.2 and 42.2 ± 5.8 kJ⋅mol−1 for the reduction of uranyl acetate, at pH values of ∼4.5 and ∼5.0, respectively. These values indicate that the reaction is controlled by the surface chemical processes. In addition, the complete reduction of aqueous U(VI) to UO 2 product was first observed for the reactions at pH ∼4.0 to ∼5.5 when the temperature was ≥75 °C. Conversely, non-stoichiometric UO 2+x (s) (0 < x ≤ 0.67) was found at lower temperatures within the same pH range, and also at 85 °C with a reaction pH of ∼9.5. Moreover, the ratio of reduced U(IV/V) on pyrite surfaces increased gradually over time, indicating that reaction time played a significant role in the reduction products. The findings are essential not only for the safety assessment of the high-level radioactive waste repository, but also for understanding the metallogenic mechanism of U(IV)-bearing ore deposits under the relevant anaerobic and hydrothermal conditions. [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]

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]

The toxic cyanides in cyanide residues produced from cyanidation process for gold extraction are harmful to the environment. Pyrite is one of the main minerals existing in cyanide residues. In this work, the interaction of cyanide with pyrite and the decyanation of pyrite cyanide residue were analyzed. Results revealed that high pH value, high cyanide concentration, and high pyrite dosage promoted the interaction of cyanide with pyrite. The cyanidation of pyrite was pseudo-second-order with respect to cyanide. The decyanation of pyrite cyanide residue by Na2SO3/air oxidation was performed. The cyanide removal efficiency was 83.9% after 1 h of reaction time under the optimal conditions of pH value of 11.2, dosage of 22 mg·g−1, and air flow rate of 1.46 L·min−1. X-ray photoelectron spectroscopy analysis of the pyrite samples showed the formation of Fe(III) and FeSO4 during the cyanidation process. The cyanide that adsorbed on the pyrite surface after cyanidation mainly existed in the forms of free cyanide (CN−) and ferrocyanide (Fe(CN)64−), which were effectively removed by Na2SO3/air oxidation. During the decyanation process, air intake promoted pyrite oxidation and weakened cyanide adsorption on the pyrite surface. This study has practical significance for gold enterprises aiming to mitigate the environmental impact related to cyanide residues. [ABSTRACT FROM AUTHOR]

The Maevatanana gold deposit in Madagascar is a quartz-vein type gold deposit hosted in a greenstone belt, and its genesis is highly controversial. This article conducts elemental geochemical analysis and dating of the Maevatanana gold deposit, and explores the mineralization age and process of the Maevatanana gold deposit in Madagascar. The gold content of gneiss is 1.11x10-9 ~ 80.8 x10-9, with an average of 19.55x10-9; pyrite is the main gold-bearing mineral in gneiss, with a Re-Os isotopic age of 752±27 Ma. The gold grade of the gold-bearing quartz vein is 26.44x10-6 ??? 6???? 132.22x10-6, and pyrite is the main gold-bearing mineral. The Re-Os isotopic age of pyrite in the gold-bearing quartz vein is 535±26 Ma, representing the mineralization age of the Maevatanana gold deposit. The Re-Os isotope isochron ages of two phases of pyrite correspond to the time of two collisions during the Pan African orogeny event. The gold content in gneiss is much higher than the average grade of the crust, and encapsulated gold can be seen in pyrite. The Re-Os isotopic age of pyrite indicates intrusion of granite and gabbro at 752±27 Ma. The Madagascar terrane underwent extensive metamorphism from greenschist to amphibolite facies, and gold in volcanic sedimentary rocks was activated, migrated, and enriched to form a source layer. The mineralization age of the gold-bearing quartz vein is 535 ± 26 Ma, which is consistent with the age of the Cambrian post collisional A-type granite in central northern Madagascar. Field evidence and geochemical data indicate a close genetic relationship between the Maevatanana gold deposit and the Cambrian post collisional A-type granite. During the process of magma ascending, the high-Si melts entered the magma and gradually evolved into ore-forming fluids, which enter the host structures and enrich mineralization. [ABSTRACT FROM AUTHOR]

Sulfurous iron minerals with recovery value are contained in a lead-zinc tailing in Fujian Province, China. However, the sulfurous iron minerals are depressed by lime in the early lead-zinc flotation, therefore it is necessary to use appropriate activators to improve the floatability of the mineral. The property of flotation foam can directly reflect the quality of the flotation index. The addition of activators can also change the properties of flotation foam. In this paper, an effective activator combination was selected through actual mine tests and foam analysis. The mineralogical study of the lead-zinc tailing was first carried out through chemical multi-element analysis and XRD. The flotation tests on the recovery of sulfurous iron ore by different activators were carried out. Finally, a foam scanning analyzer was used to test and analyze the frothing performance and froth stability of the slurry under different activation conditions. The results showed that the dispersion-activation flotation and dispersion-combined activation flotation can help to improve the frothing performance of the slurry and improve the flotation indexes. At the same time, the enhanced activated flotation can also reduce the froth stability indexes (FSI) to less than 20 s, and the reduction of the froth stability can help to improve the flotation recovery. For each activation flotation process that achieves the best flotation index, the frothing performance and foam stability of the pulp is close to that of the flotation tests index. [ABSTRACT FROM AUTHOR]

An enormous quantity of titanium slag has caused not merely serious environment pollution, but also a huge waste of iron and sulfur resources. Hence, recycling iron and sulfur resources from titanium slag has recently been an urgent problem. Herein, hematite nanoparticles were fabricated through a pyrite reduction approach using as-received titanium slag as the iron source and pyrite as the reducing agent in an nitrogen atmosphere. The physicochemical properties of the hematite nanoparticles were analyzed using multiple techniques such as X-ray diffraction pattern, ultraviolet–visible spectrophotometry, and scanning electron microscopy. The best synthesis conditions for hematite nanoparticles were found at 550 °C for 30 min with the mass ratio of 14:1 for titanium slag and pyrite. The results demonstrated that hematite nanoparticles with an average particle diameter of 45 nm were nearly spherical in shape. The specific surface area, pore volume, and pore size estimated according to the BET method were 19.6 m2/g, 0.117 cm3/g, and 0.89 nm, respectively. Meanwhile, the fabricated hematite nanoparticles possessed weak ferromagnetic behavior and good absorbance in the wavelength range of 200 nm-600 nm, applied as a visible light responsive catalyst. Consequently, these results show that hematite nanoparticles formed by the pyrite reduction technique have a promising application prospect for magnetic material and photocatalysis. [ABSTRACT FROM AUTHOR]

The acid pollution produced from coal gangue piles is a global environmental problem. Terminal technologies, such as neutralization, precipitation, adsorption, ion exchange, membrane technology, biological treatment, and electrochemistry, have been developed for acid mine drainage (AMD) treatment. These technologies for treating pollutants with low concentrations over a long period of time in coal gangue piles appear to be costly and unsustainable. Conversely, in situ remediation appears to be more cost-effective and material-efficient, but it is a challenge that coal producing countries need to solve urgently. The primary prerequisite for preventing acidic pollutants is to clarify the oxidation mechanisms of coal gangue, which can be summarized as four aspects: pyrite oxidation, microbial action, low-temperature oxidation of coal, and free radical action. The two key factors of oxidation are pyrite and coal, and the four necessary conditions are water, oxygen, microorganisms, and free radicals. The current in situ remediation technologies mainly focus on one or more of the four necessary conditions, forming mixed co-disposal, coverage barriers, passivation coatings, bactericides, coal oxidation inhibitors, microorganisms, plants, and so on. It is necessary to scientifically and systematically carry out in situ remediation coupled with various technologies based on oxidation mechanisms when carrying out large-scale restoration and treatment of acidic coal gangue piles. [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]

Fe(III) has been proved to be a more effective oxidant than dissolved oxygen at ambient temperature, however, the role of Fe(III) in pyrite acidic pressure oxidation was rarely discussed so far. In this paper, in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation environment. The results illustrated that increasing Fe(III) concentrations led to raising in redox potential of the solution, and decreased passivation of pyrite caused by deposition of elemental sulfur. Reduction of Fe(III) at pyrite surface was a fast reaction with low activation energy, it was only slightly promoted by rising temperatures. While, the oxidation rate of pyrite at all investigated Fe(III) concentrations increased obviously with rising temperatures, the anodic reaction was the rate-limiting step in the overall reaction. Activation energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(III) concentration was increased from 0.05 to 0.50 g/L, showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(III) concentrations, while, it gradually turned to be diffusion control with increasing Fe(III) concentrations. [ABSTRACT FROM AUTHOR]

Late Middle Palaeolithic Neandertals in France are known to have engaged in the collection and grinding of black minerals rich in manganese dioxide (MnO2), generally presumed for symbolic use as powdered pigments. However, lab-based experiments conducted by Heyes and colleagues (Sci Rep 6: 22159, 2016) have shown that the addition of powdered MnO2 to wood turnings both reduces the temperature required for combustion by ca. 80–180 °C and significantly increases the rate of combustion. This special pyrotechnic property of powdered MnO2 may have been observed and leveraged by Neandertals to aid in fire making—a technology known to Neandertals in this region by at least 50,000 years ago. To test this idea, a series of actualistic fire-making experiments were performed to determine the practical applicability of MnO2 as a tinder-enhancing additive. The flint-and-pyrite percussive fire-making method was employed to produce sparks that were directed onto eight different types of tinder common to temperate Northwest Europe to determine if and to what degree the addition of MnO2 powder improved their ability to capture sparks that then propagate into glowing embers. The results show that MnO2 does indeed considerably improve the ignition efficiency of tinder material over untreated tinder, both in terms of the point of first ignition and the total number of ignitions achieved. It was observed, however, that the incidental addition of pyrite dust onto a tinder over the course of an experiment also appeared to improve its ability to capture sparks. Supplemental experiments using tinder pre-mixed with powdered pyrite confirmed this hypothesis, suggesting pyrite powder similarly expedites fire production. While this finding may raise questions regarding the need for collecting MnO2 for this purpose, its potential utility may lie in (1) its relative softness compared to pyrite, making it much easier to grind or scrape into powder, and (2) the greater potential for MnO2-bearing deposits to yield larger quantities of usable raw material compared to pyrite-bearing outcrops, making it relatively more abundant in some areas. Thus, when available, it is clear that adding MnO2 to tinder would have noticeably reduced the time and energy required to produce fire, making it a potentially novel Neandertal innovation complementary to the fire-making process. [ABSTRACT FROM AUTHOR]

As the global demand for tellurium (Te) increases, it is crucial to develop efficient recovery methods that consider existing supply streams. This research combines gravity separation and froth flotation processes to enhance the recovery of Te minerals from tailings produced during the beneficiation of copper porphyry ores. Prior to processing, a systematic and comprehensive characterization study of copper tailing (CT) samples was conducted to examine the deportment of Te minerals in different mineral phases and to understand their locking and liberation behavior. Characterization techniques included inductively coupled plasma mass spectrometry (ICP-MS) and TESCAN's integrated mineral analysis (TIMA). Copper tailing characterization showed that minerals with gold (Au), silver (Ag), bismuth (Bi), and Te were present in various forms, including native Au, electrum, tellurides, and sulfosalts. TIMA revealed that >90% of these minerals were primarily hosted in pyrite as less than 10 µm inclusions in the CT. TIMA also revealed that Te minerals exhibited fine-grained liberation of less than 20 μm. Moreover, TIMA results showed that >80% of mica and other silicate minerals were concentrated in size fractions < 38 μm, suggesting that desliming processes would positively impact Te enrichment. The results from the processing tests showed a Te recovery rate of ~77% and a Te enrichment ratio of 13 when using the combination of gravity separation and froth flotation at 90 g/t xanthate collector and 50 g/t glycol frother. The findings from this study show a significant potential for Te recovery from unconventional sources if appropriate physical beneficiation approaches are adopted. [ABSTRACT FROM AUTHOR]

This study investigates the correlation between the electronic structure of the active sites on mineral surfaces and their adsorption capacity. Density functional theory (DFT) and flotation experiments are employed to examine the bonding behavior and adsorption enthalpy of ethylxanthate on pyrite (1 0 0) and arsenopyrite (0 0 1) surfaces. The results indicate that ethylxanthate adsorbs more significantly on pyrite than on arsenopyrite. The adsorption is chemical, primarily occurring through the orbitals of sulfur in the ethylxanthate and iron on the mineral surface. Compared to arsenopyrite, the d-band center of the iron atoms on the surface of pyrite is closer to the Fermi level; thus, the adsorption strength of ethylxanthate on the pyrite surface is greater than on arsenopyrite. The d-band centers of pyrite and arsenopyrite exhibit a direct relationship with their adsorption capacity. [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]

Copyright of Technology of Water Treatment is the property of Technology of Water Treatment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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]

In the formerly glaciated terrains in the northern hemisphere and countries such as Finland, till is the most common sediment covering the bedrock. Specifically, indicator or heavy mineral studies utilising till as a vector for mineral deposits undercover have been successful. The pyrite trace-element composition from in situ mineral analyses has been shown to be an effective discriminator between different mineral deposit types, and this has led to research using heavy mineral pyrite in till to identify potential mineral deposits in a given area. However, pyrite is easily oxidised in till beds, and thus, alternative methods should be considered. Goethite pseudomorphs are more commonly found in the till sediments as remnants after pyrite oxidation. This study evaluates trace element compositions of goethitised pyrite recovered in the till beds from central Lapland in northern Finland. Intra-grain trace-elemental variations gathered using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) between the intact pyrite core and oxidised rim demonstrated complex dynamics and variations between different trace-element values. For example, Cu, V and Mn exhibited elevated trace-element values in the goethite rim compared to the pyrite core. However, elemental ratios such as Ni/As and Co/Ni remain stable between the pyrite core and oxidised rim. Therefore, these ratios have the potential to be used as a discriminating tool between the pyrite core and oxidised rim. In addition, nanoscale variabilities using focused ion beam (FIB) and transmission electron microscopy (TEM) were utilised to inspect possible nano inclusions within the studied heavy mineral grain. The FIB and TEM studies revealed a nanocrystalline pyrite nodule observation within the goethite rim. [ABSTRACT FROM AUTHOR]