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This study developed a new method for in situ measurement of stable Mo isotope ratio using femtosecond laser ablation connected to a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). We assessed how laser fluence, laser repetition rate, and signal intensity impact Mo isotope mass fractionation, using synthetic molybdenite Mo-H8 as the reference material. Findings reveal that the laser repetition rate has negligible impact on Mo isotope fractionation, while signal intensity and laser fluence slightly influence the precision of d98Mo. Significant signal intensity disparities between samples and reference materials can markedly affect the results of Mo isotopes. We analyzed natural molybdenite samples from various deposits in China with this new method, with the optimal laser parameters including a repetition rate of 10 Hz, a spot size of 20 mm, and a fluence of 1 J cm-2. The d98MoNIST SRM 3134 values for nine natural samples (GD-1, GD-2, YN-1, YN-2, YN-3, SX-1, SX-2, SX-3, and GX-1) align with those obtained by solution nebulization MC-ICP-MS within analytical uncertainty, demonstrating the accuracy of this new in situ Mo isotope analytical method. This new technique offers a reliable alternative to solution nebulization MC-ICP-MS in bulk analysis, enabling precise detection of Mo isotope ratio variations at a finer scale, which provides valuable insights into mineralization processes. [ABSTRACT FROM AUTHOR]

The East Qinling Molybdenum Belt (EQMB), which is located on the southern margin of the North China Craton (NCC), is the largest Mo province in the world. This belt hosts a significant number of Mesozoic magmatic-hydrothermal Mo deposits and a small portion of pre-Mesozoic Mo deposits. Understanding the mineralization timing and mechanism of the unique pre-Mesozoic Mo deposits is essential to comprehend the evolution of the EQMB, the pre-Mesozoic Mo enrichment, and the Mesozoic Mo mineralization event. The recently discovered Zhaiwa deposit is a porphyry Mo deposit located in the Xiong'er Terrane of the EQMB. In this study, five molybdenite samples from the Mo-bearing quartz veins were analyzed for Re-Os isotopes composition. These samples yield an isochron age of 1794 ± 45 Ma, which represents the age of mineralization. The mineralization is mostly hosted within the biotite-amphibole plagiogneiss and granite porphyry. LA-ICP-MS U-Pb data of zircons constrain the crystallization age of the granite porphyry to be at 1791 ± 16 Ma. The close spatial and temporal association suggests that the granite porphyry is the causative rocks of the Mo mineralization. The δ34S values of pyrite vary from 5.3 to 6.8‰, suggesting that the S was mainly derived from magmatic source. The intrusion of magmas and associated Mo mineralization are contemporaneous to the regional Xiong'er volcanism that occurred during the late Paleoproterozoic. The Xiong'er volcanism was triggered by partial melting of lithospheric mantle in an extensional setting. The results of our study provide robust evidence for a late Paleoproterozoic Mo metallogenic event along the southern margin of the NCC. Future exploration should also consider the potential of late Paleoproterozoic porphyry Mo mineralization existing in the EQMB, which is closely associated with the Xiong'er volcanism. [ABSTRACT FROM AUTHOR]

The inhibiting mechanism of high pH on the molybdenite flotation was studied using an experimental and DFT method. The experimental results found that adverse effects of pH on molybdenite flotation should be attributed to the adsorption of OH− on molybdenite [100] surface (MS100). The DFT results show the adsorption energy of H2O/OH− to molybdenite [001] surface (MS001) and MS100 is −8.61/288.30 kJ·mol−1 and −226.81/−302.44 kJ·mol−1. These indicate that H2O is weakly adsorbed on MS001, while OH− is not. Both H2O and OH− can be adsorbed onto MS100. The adsorption energy of OH− to MS100 is much stronger than that of H2O. The results of state density and charge transfer of the adsorption of OH− on MS100 further show that OH− can be chemically adsorbed on MS100 through the bonding of the O atom of OH− and the Mo atom of MS100. This causes a significant reduction in the MS100 hydrophobicity and deteriorates the fine molybdenite flotation. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources 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.)

This is an article in the field of mineral processing engineering. Molybdenum has many good physical and chemical properties and is widely used in many fields. Molybdenum is mainly derived from molybdenite, but the resources of the easily beneficiated molybdenum ore have been gradually reduced after long-term development. Nowadays, talc-type and other refractory molybdenum ores have gradually become the focus of research. The separation of talc and molybdenite is a difficult point in the separation of talc-type molybdenum ores. The two has similar surface structures and natural floatability, and the separation is very difficult. This article summarizes the current research progress of talc-type molybdenum ore beneficiation technology and reagents, and proposes to strengthen the research and development of selective grinding of talc-type molybdenum ores and organic macromolecular reagents, and deepen the mechanism and effect of reagents and mineral surfaces. The study of the raw ore technological mineralogy is an important direction for sorting the talc-type molybdenum ore in the future.

Analyzing sulfur (S) and molybdenum (Mo) isotope ratios in molybdenite, the most common sulfide mineral, is crucial for studying the genesis of ore deposits. However, it is necessary to prepare matrix-matched reference materials for molybdenite. In this study, we employed two different techniques, the high-temperature-high-pressure (HTHP) technique and the rapid hot-pressing technique, to synthesize molybdenites and assessed their suitability as reference materials for in situ Mo and S isotope analysis in molybdenite. The molybdenites synthesized through HTHP and rapid hot-pressing exhibit smooth surfaces and dense structures, making them suitable as reference materials for in situ Mo and S isotope analysis, respectively. These synthesized molybdenites exhibit homogeneous Mo and S isotope compositions based on a large number of LA-MC-ICP-MS measurements. The mean δ98MoNIST SRM 3134 values of 0.70 ± 0.06‰ (n = 4, 2SD) and 0.70 ± 0.05‰ (n = 4, 2SD) determined by solution nebulization MC-ICP-MS are suggested as recommended δ98Mo/95Mo values for Mo-H8 and Mo-P. The mean δ34SV-CDT value of −0.22 ± 0.10‰ (n = 9, 2SD) determined by elemental analyzer isotope ratio mass spectrometry (EA-IRMS) is suggested as a recommended δ34S/32S value for Mo-H8 and Mo-P. Therefore, we recommend combining ultrafine powders with a high-temperature–high-pressure technique and/or a rapid hot-pressing technique to synthesize reference materials for isotopic analysis of other minerals. [ABSTRACT FROM AUTHOR]

Re‐Os isotope‐dilution geochronology has been widely used to date the timing of molybdenite, pyrite and chalcopyrite formation across a variety of geological settings. However, in situ methods have been impeded by the isobaric interference of 187Re on 187Os. In situ Re‐Os geochronology using LA‐ICP‐MS/MS has been shown to be a useful technique to chemically separate Os from Re, as Os reacts with CH4 to create higher‐mass reaction products, which can then be measured with minimised interference of 187Re. However, application of the method requires matrix‐matched primary reference materials, e.g., age‐homogenous molybdenite amenable to laser ablation. Here, we characterise and present two new molybdenite mineral reference materials for in situ Re‐Os geochronology by LA‐ICP‐MS/MS, verified by ID‐TIMS Re‐Os measurements. We also present case studies from molybdenite samples with varying Re mass fractions and Re‐Os age mapping. The method provides accurate and precise age data, with excellent precision for high Re samples. The benefits of the LA‐ICP‐MS/MS approach include: (1) simple sample preparation, (2) rapid data acquisition, (3) targeting of specific textural domains including growth zones and (4) the ability to simultaneously collect trace elements used to link the timing and conditions of ore‐formation. [ABSTRACT FROM AUTHOR]

This research mainly investigated the flotation kinetics of molybdenite in seawater based on four flotation models. Molybdenite flotation presented an excellent agreement with the first-order model with rectangular distribution. The ultimate cumulative recovery (R∞) and flotation rate constant (k) of molybdenite decreased in seawater, mainly due to the divalent cations, with the impact of Mg2+ being significantly greater than that of Ca2+. The addition of sodium silicate (SS) and sodium hexametaphosphate (SH) increased the flotation recovery and rate, probably due to the positive role of dispersants on preventing the attachment of seawater precipitates onto molybdenite surface. In addition, three different stages of flotation kinetics were proposed to reveal the molybdenite flotation for the first time, with the highest flotation recovery and rate being found at Stage I. However, seawater showed a negative role on Stage I, i.e. resulting in a longer duration and lower recovery, as compared to that in pure water. The addition of both SS and SH improved the flotation kinetics at Stage I, with SH being more significant. Therefore, it is more feasible to eliminate the negative effects of seawater on molybdenite flotation at the initial stage (Stage I). [ABSTRACT FROM AUTHOR]

The Kirazlı deposit is located at the center of the Biga Peninsula metallogenic province, in a geological setting characterized by an extensional tectonic environment. A NNW-SSE trending high-sulfidation (HS) orebody with a total reserve of 33.86 Mt @ 0.69 g/t Au and 9.42 g/t Ag lies beneath the Kirazlı Main zone. A porphyry Cu orebody hosted by Eocene intrusive and volcanic rocks has been intersected by drilling within its vicinity. The HS epithermal deposit is hosted by a partly silicified and brecciated Oligocene volcanic and volcaniclastic sequence consisting mainly of basaltic andesite lava flow and lithic/crystal tuff. Lithogeochemistry and zircon U-Pb radiometric ages allow us to distinguish three distinct high-K calc-alkaline magmatic events at ca. 41, 38, and 32 Ma, sourced by metasomatized mantle melts, which have interacted with the crust during their ascent. Porphyry Cu mineralization took place at 36.7 ± 0.4 Ma (muscovite 40Ar/39Ar age) with subsequent re-opening and base metal deposition. Crosscutting quartz-pyrite-molybdenite veins were emplaced at 33.6 ± 0.2 Ma (molybdenite Re-Os age), and followed by the HS epithermal Au-Ag event at ca. 31 Ma, based on a previous study. Our radiometric data indicate that the Kirazlı deposit has recorded a long-lasting Cenozoic magmatic and metallogenic evolution during about 10 Myr. Our study demonstrates that successive, independent, and overprinting, but genetically unrelated, HS epithermal precious metal, hydrothermal Mo, base metal, and porphyry Cu systems have been active at the same location during protracted extensional tectonics of the Biga Peninsula. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing 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.)

This article, published in Chemical Communications, explores the electrochemical reduction of CO2 on molybdenite (MoS2) electrocatalysts. The study utilizes scanning electrochemical cell microscopy (SECCM) to directly observe the activity of different surface structures of MoS2 in reducing CO2. The findings reveal that nanoscale defects, particularly those with exposed edge planes, demonstrate higher overall activity in CO2 reduction compared to the relatively inactive basal plane. This research offers valuable insights for the development of cost-effective electrocatalysts for large-scale CO2 electrolysis. The study focuses on the electrochemical reduction of carbon dioxide (CO2) on 2H-MoS2 using scanning electrochemical cell microscopy (SECCM). It investigates the impact of various structural features, such as creases, step edges, and nanoflakes, on the electrocatalytic activity of 2H-MoS2. The results indicate that creases and step edges exhibit enhanced CO2 reduction activity compared to the bulk material, while nanoflakes are highly active but not selective for CO2 reduction. These findings contribute to our understanding of the structure-activity relationships of 2H-MoS2 in CO2 electroreduction. [Extracted from the article]

Background. During flotation enrichment of Cu-Mo ores at a mining and metallurgy enterprise, flotation reagents are used, including imported frother T-92. Meanwhile, in the republic there is an opportunity for its import substitution, based on local raw materials. Purpose: development of new reagents for depression of flotation-active gangue, without reducing the extraction of molybdenum into an industrial molybdenum product. Methodology. The flotation machine FML-3 manufactured by NPR "Mekhanobr Technika" (RF), flotation reagent T-92 were used. To compare the surface activity of surfactants and the efficiency of rare metal sulfide extraction from flotation pulp, elemental analysis was performed via Agilent 7500 ICP. Originality. Two highly efficient foaming agents have been created from local technogenic raw materials, exhibiting operational properties at a level no worse than the standard flotation reagent T-92. Findings. Foaming capacity, foam stability, depression of flotation-active gangue, without reducing Mo extraction into molybdenum middlings, of new import-substituting foaming agents have been determined. [ABSTRACT FROM AUTHOR]

The molybdenum oxidation rate of a large-scale tungsten molybdenum mine reaches 42. 45%. The intimate association of molybdenum, tungsten, iron, and fluorite minerals, with fine particle size, and high content of calcium-magnesium silicates, carbonates, and clay minerals, distributed extremely uneven, poses challenges in ore-dressing. To address this complexity in processing polymetallic ores, an industrializable and relatively simple crushing and grinding magnetic separation desliming flotation process was adopted. This process yielded molybdenum sulfide concentrate (containing 45.76% molybdenum), molybdenum oxide - tungsten oxide concentrate (containing 15.88% molybdenum and 22.65% tungsten), and iron concentrate (containing 63.11% iron). The recovery rates of molybdenum, tungsten, and iron were 67.75%,51.84%, and 36.44% respectively, achieving effective resource recovery. Pre-desliming before flotation facilitates smooth flotation operations, reduces reagent consumption, and stabilizes the recovery of valuable minerals. [ABSTRACT FROM AUTHOR]

The flotation of unoxidized and oxidized molybdenite fines is a challenging job worldwide. In this work, dodecylamine (DDA) was developed as a potential collector to improve the flotation of molybdenite fines with and without oxidation. The flotation behaviors and interaction mechanisms were probed through flotation tests, contact angle, Zeta potential, Scanning Electron Microscope-Energy Dispersive Spectrometer(SEM-EDS), and X-ray Photoelectron Spectroscopy (XPS). The flotation tests revealed that DDA improved the flotation of unoxidized or oxidized molybdenite fines efficiently. The results of Zeta potential, contact angle, and SEM-EDS uncovered that a substantial number of DDA species adsorbed on both fresh and oxidized molybdenite faces and edges, thus enhancing their hydrophobicity. XPS analysis further manifested that RNH2 and RNH3+ adsorbed on the S atoms of fresh faces through hydrogen bonding. Meanwhile, RNH2 and RNH3+ mainly adsorbed on fresh edges via chemical bonding between amine groups and Mo sites and electrostatic force. For oxidized molybdenite, RNH2 and RNH3+ interacted with oxidized faces through hydrogen bonding while adsorbed on oxidized edges via hydrogen bonding and electrostatic interaction. [ABSTRACT FROM AUTHOR]

The Samba Cu deposit is located in pre-Katangan Supergroup basement metavolcanic rocks of the Central African Copperbelt in Zambia. To better understand the formation of the Cu deposit, we use geochronologic, geochemical, and S isotopic data obtained for the deposit's host rocks and sulfide minerals. Laser ablation-inductively coupled plasma-mass spectrometric (LA-ICP-MS) dating of zircon from host rocks, including quartz-sericite schist and biotite-sericitechlorite schist, yields ages of 1967 ± 17 Ma and 1960 ± 20 Ma, which are interpreted as the crystallization ages of the original volcanic rocks. Re-Os analyses of molybdenite intergrown with chalcopyrite constrain sulfide deposition to 548.1 ± 7.5 Ma and 524.1 ± 7.3 Ma, which correspond to the timing of the Cu mineralization. LA-ICPMS U-Pb analyses of metamorphic rutile from the biotite-sericite-chlorite schist yield a U-Pb age of 508.3 ± 6.6 Ma, which is interpreted to represent the age of regional metamorphism. The new data suggest that the Cu mineralization at Samba was synchronous with the Lufilian orogeny. [ABSTRACT FROM AUTHOR]

A new method for the preparation of hydrodesulfurization catalysts based on the mechanochemical treatment of molybdenum under cryogenic conditions was proposed. The results of direct one-stage mechanochemical grinding of molybdenum at 77 K in gaseous media of He and H2 and in liquid N2, as well as in the presence of solid Ar, are reported. The physicochemical properties of the cryopowders and their catalytic activity in the model hydrodesulfurization reactions of dibenzothiophene and diesel fraction were examined. [ABSTRACT FROM AUTHOR]

Developing cost‐effective and efficient photo‐Fenton catalysts is crucial for advancing photo‐Fenton technology. MoS2 is a representative transition metal disulfide with attractive photoresponsiveness, making it ideal for preparing composite photo‐Fenton catalysts. In this study, natural molybdenite was innovatively utilized as a source of MoS2 (OM) to synthesize a low‐cost and efficient Fe@MoS2 (OMF) composite photo‐Fenton catalyst by comminution and adsorption, which was then applied to the remediation of antibiotic‐contaminated water. The OMF composites exhibited significant catalytic activity, with a kinetic rate constant of 0.022 min−1, which was 3.1 times higher than that of the original OM (0.007 min−1), indicating a 3% increase. This was attributed to the synergistic effect of many photogenerated electrons and reversible Mo4+/Mo6+ redox pairs, which accelerated the regeneration of Fe2+. After three cyclic tests, the concentrations of dissolved Fe2+ and Mo2+ ions remained below 0.38 mg/L and 0.17 mg/L, respectively. This indicates the high reusability of the catalyst in cyclic experiments. Ultimately, the main active species, •OH and •O2−, were generated during the photo‐Fenton process, contributing significantly to TC degradation. This study may serve as a reference for the development and application of natural mineral composite photo‐Fenton catalysts in the treatment of organic wastewater. [ABSTRACT FROM AUTHOR]

In the flotation separation process of a Cu-Mo-W polymetallic ore, the wastewater from the scheelite cleaning flowsheet contains large numbers of residual flocculants and metal ions, and the separation of chalcopyrite and molybdenite requires a large number of environmentally harmful depressants. Therefore, it is necessary to find new methods to reduce the environmental and cost pressures of wastewater treatment and the use of depressants. In this work, the flotation wastewater from the scheelite cleaning flowsheet for the separation of chalcopyrite and molybdenite by selective surface passivation was investigated for the first time. Flotations of single minerals and artificially mixed minerals with or without immersion pretreatment in the presence and absence of aeration were performed. The results showed that pulp pH had no effect on the flotation of either mineral, and a molybdenite recovery of 93.22% with a chalcopyrite recovery of 10.77% was achieved under the conditions of 10 days of immersion pretreatment with aeration, 350 mg/L of kerosene, and 100 mg/L of MIBC. By combining the electrochemical cyclic voltammetry analysis and characterization by XRD and SEM, the selective surface passivation mechanism of chalcopyrite was discussed, which could be due to the coverage of the insoluble oxidation products, especially jarosite. This work has simultaneously achieved the depressant-free flotation separation of molybdenite and chalcopyrite and the reuse of scheelite flotation wastewater, which is of great significance for environmental protection and cost saving. [ABSTRACT FROM AUTHOR]

The depression of pyrite in the flotation separation of molybdenum-sulfur (Mo-S) mixed concentrate has become a significant issue. This study aimed to examine the process of separating molybdenite and pyrite in the presence of sodium humate (NaHA). The results of micro-flotation tests indicated that NaHA exhibited significant pyrite depression capabilities and displayed remarkable selectivity toward both pyrite and molybdenite. Real ore flotation experiments have shown that adding 22.5 mg/L of NaHA to the pulp of Mo-S mixed concentrate at a pH of 6.5, the flotation indexes achieved 46.01% Mo grade and 90.11% Mo recovery. It is noteworthy that the dosage of NaHA was significantly lower compared to the 505 utilized in the mineral processing plant. Contact angle measurements revealed that NaHA effectively increased the surface hydrophilicity of pyrite. Adsorption amount measurements, zeta potential measurements, and Fourier infrared spectroscopic (FT-IR) analysis indicated that the adsorption capacity of NaHA on pyrite was higher than on molybdenite. NaHA had a highly selective inhibitory capacity for Mo-S mixed concentrate and is an ideal separation depressant. [ABSTRACT FROM AUTHOR]

The leaching of molybdenum from molybdenite by oxygen pressure water leaching method was studied. The effects of ore size, oxygen partial pressure, temperature and stirring speed on oxidation of molybdenite were investigated, and the distribution of oxidation products in solid and liquid phases was discussed. The results show that the oxidation of molybdenite can be promoted by the decrease of ore particle size and the increase of oxygen partial pressure, temperature and stirring speed. The oxidation products first enter the liquid phase. When the liquid phase is saturated with MoO42-, the oxidation products will enter the slag phase in the form of MoO3. The oxidation of molybdenum during oxygen pressure water leaching of molybdenite can be described by the unreacted nuclear shrinkage model. The reaction rate is controlled by the mixed control model, and the apparent activation energy is 40. 55 kJ/mol. [ABSTRACT FROM AUTHOR]

This is an essay in the field of mineral processing engineering. A molybdenum mine in Henan Province belongs to the skarn type molybdenum mine, which has the characteristics of extremely fine embedded particle size and high mud mineral content, and the molybdenum has suffered poor recovery. This paper systematically analyzed the ore properties and production status and analyzed the main problems existing in the production. In order to meet the needs of the 4000 t/d capacity expansion and reconstruction of the ore dressing plant, and to synergistically strengthen the recovery of fine-grained molybdenite particles, a cyclonic-static microbubble flotation column was proposed to add combined with the structural characteristics and separation advantages. The research results show that the molybdenum ore was embedded with micro-fine size, and -0.038 mm and -0.020 mm molybdenite accounted for 75.80% and 38.68%, respectively. Moreover, the ores contained a large amount of epidote, montmorillonite, chlorite and other argillaceous minerals, and the content of argillaceous minerals in some pit mouths was more than 40%. The existing flotation process has suffered poor recovery in the fine-grained particles, and the loss of molybdenum with -0.020 mm size in the tailings accounted for more than 50%. Laboratory flotation test results show that the cyclone-static microbubble flotation column had a good flotation effect on molybdenum recovery in total tailings and rougher tailings, and the concentrate enrichment ratio and molybdenum recovery rate were obviously better than flotation machine. The engineering practice further shows that the cyclone-static microbubble flotation column played a role in regaining better recovery for the existing flotation column, and the molybdenum recovery rate after the expansion was increased by more than 4 percentage points, and the loss of fine-grained molybdenite particles in tailings were significantly reduced, which achieved significant economic benefits.

The Talnikovoye ore field, where previous academic research and exploration works revealed porphyry copper mineralization, is described. Our data show that the mineralization is confined to the Turonian granodiorite and quartz diorite intrusions (91 Ma, U–Pb metohod) and accompanying hydrothermal–explosive breccias. Biotite–epidote–chlorite propylites are widespread within the ore field; in the southern part, quartz–sericite phyllic alteration is superimposed on the K-feldspar alteration halo. The ore occurs in zones of intense quartz, chlorite–epidote–quartz (with chalcopyrite and molybdenite), sulfide-potassium feldspar–quartz (with chalcopyrite and bornite), and sulfide–quartz–sericite (with chalcopyrite) stockwork veining with copper–molybdenum mineralization. They have moderate concentrations of Cu (0.1–0.3%, reaching 1.1%) and Mo (up to 0.1%), low concentrations of Au (up to 0.1 g/t) and Ag (up to 2.6 g/t), and have a Cu–Mo–(Au, Ag, Pb, Zn, Sb, and As) geochemical signature. Fluid inclusion data suggest the formation of quartz in mineralized veinlet during the magmatic–hydrothermal transition (430–150°С) with solutions at high (50 wt % NaCl equiv.), medium and low concentrations (5–18.9 wt % NaCl equiv.) involved under the cooling–dilution scenario. The values of the main geochemical indicators, such as Cu/Mo (30–60) and Cu/Au (>1 × 105) ratios allowed us to assign the Talnikovoye ore field to the porphyry copper–molybdenum type characteristic of continental-margin volcano-plutonic belts formed on the mafic island-arc basement. The geochemical parameters of ore-bearing porphyry granitoids indicate their formation in a setting of a subduction-to-transform plate boundary transition. [ABSTRACT FROM AUTHOR]

In this study, GX2 was applied as a new high-efficiency chalcopyrite depressant to selectively separate molybdenite from Cu-Mo sulfide ores. The flotation performance and its interaction mechanisms with chalcopyrite and molybdenite were investigated using single-mineral and artificial-mixed-ore flotation, contact angle measurements, zeta-potential measurements, infrared spectroscopy, and X-ray optoelectronic spectrum analysis. The results indicated that molybdenite could be selectively separated from chalcopyrite under the optimal flotation conditions of pH 9.0, 80 mg/L GX2, 20 mg/L kerosene, 10 mg/L MIBC, and a flotation time of 3 min, while the molybdenite and chalcopyrite recoveries were around 90% and 5%, respectively. It was confirmed that GX2 could save ten times the depressant dosage compared to that of the Na2S baseline to achieve a similar separation efficiency. The contact angle test, zeta potential, infrared spectrum, and XPS results show that GX2 may be adsorbed on the surface of chalcopyrite via chemical adsorption, and the hydrophilic substances formed change its hydrophobicity, whereas the effect on the floatability of molybdenite is small, resulting in the excellent separation efficiency of chalcopyrite and molybdenite via flotation. [ABSTRACT FROM AUTHOR]

The Dahongshan Fe‐Cu (‐Au) deposit is a superlarge deposit in the Kangdian metallogenic belt, southwestern China, comprising approximately 458 Mt of Fe ores (40% Fe) and 1.35 Mt Cu. Two main types of Fe‐Cu (‐Au) mineralization are present in the Dahongshan deposit: (1) early submarine volcanic exhalation and sedimentary mineralization characterized by strata‐bound fine‐grained magnetite and banded Fe‐Cu sulfide (pyrite and chalcopyrite) hosted in the Na‐rich metavolcanic rocks; (2) late hydrothermal (‐vein) type mineralization characterized by Fe‐Cu sulfide veins in the hosted strata or massive coarse‐grained magnetite orebodies controlled by faults. While previous studies have focused primarily on the early submarine volcanic and sedimentary mineralization of the deposit, data related to late hydrothermal mineralization is lacking. In order to establish the metallogenic age and ore‐forming material source of the late hydrothermal (‐vein) type mineralization, this paper reports the Re‐Os dating of molybdenite from the late hydrothermal vein Fe‐Cu orebody and H, O, S, and Pb isotopic compositions of the hydrothermal quartz‐sulfide veins. The primary aim of this study was to establish the metallogenic age and ore‐forming material source of the hydrothermal type orebody. Results show that the molybdenite separated from quartz‐sulfide veins has a Re‐Os isochron age of 831 ± 11 Ma, indicating that the Dahongshan Fe‐Cu deposit experienced hydrothermal superimposed mineralization in Neoproterozoic. The molybdenite has a Re concentration of 99.7–382.4 ppm, indicating that the Re of the hydrothermal vein ores were primarily derived from the mantle. The δ34S values of sulfides from the hydrothermal ores are 2‰–8‰ showing multi‐peak tower distribution, suggesting that S in the ore‐forming period was primarily derived from magma and partially from calcareous sedimentary rock. Furthermore, the abundance of radioactive Pb increased significantly from ore‐bearing strata to layered and hydrothermal vein ores, which may be related to the later hydrothermal transformation. The composition of H and O isotopes within the hydrothermal quartz indicates that the ore‐forming fluid is a mixture of magmatic water and a small quantity of water. These results further indicate that the late hydrothermal orebodies were formed by the Neoproterozoic magmatic hydrothermal event, which might be related to the breakup of the Rodinia supercontinent. Mantle derived magmatic hydrothermal fluid extracted ore‐forming materials from the metavolcanic rocks of Dahongshan Group and formed the hydrothermal (‐vein) type Fe‐Cu orebodies by filling and metasomatism. [ABSTRACT FROM AUTHOR]

In modern metallurgical industry, microwave thermal technique has many advantages as one efficient energy treatment in an electromagnetic form, such as internal self-generated heat, easy access to control a volumetric heating process, and consensus on cleanliness, convenience and high efficiency of energy use. Both permittivity and permeability of molybdenite concentrate were measured for a further discussion about its electromagnetic heating coupling. A bidirectional coupling physics field in numerical modeling was undertaken to evaluate the microwave absorption potential and dielectric heating performance of molybdenite concentrate by the multi-physics finite element method. The electromagnetic morphology and the field distribution strength were described in the microwave reaction cavity. The electromagnetic field strength and the dissipation coefficient induced by temperature variation were represented throughout the whole heat chamber and at key parts of interest. Dependent temperature distribution was compared with that being obtained from a scenario by thermal conduction with a stable heat source. The molybdenite concentrate would be heated at surrounding temperature up to 593 °C for 10 min by microwave energy that was transmitted by a rectangular waveguide. Scanning electron microscopy (SEM) patterns suggested that the polished and neat crystalline molybdenum trioxide (MoO3) products were achieved by the microwave heating process. The superiority via utilizing microwave thermal technique is expounded in the preparation strategy for molybdenum oxide or molybdenum metal. [ABSTRACT FROM AUTHOR]

This work aims to understand the distribution and migration mechanisms of U and Mo between surface sediment and water in acid mine drainage (AMD) regions near a molybdenum mining region. A series of river sediment and water samples near the Jinduicheng mining area, one of the largest deposits of molybdenite ore in Asia, were collected and analyzed. Our results indicate that: (1) The pH value of river water samples increases with distance from upstream to downstream, while the pH has poor correlation with Mo and U; (2) The content of Mo and U in the sediment are significantly higher than the background value, which suggests potential pollution; (3) The content of Mo and U in the water and sediments in the lower reaches of the Wenyu river is significantly linearly related with the distance from the mining area, suggesting that AMD is a potential source; (4) BCR analysis shows that Mo in river sediments mainly existed as the residual, while U mainly existed as the non-residual; (5) The distribution coefficient Kd(Mo) exceeds Kd(U), indicating that Mo is enriched in sediments while U is more prone to porewater. [ABSTRACT FROM AUTHOR]

Depressants are critical reagents for the selective separation of minerals in froth flotation. They serve a vital role in preferentially making the gangue minerals hydrophilic and prevent them from reporting to the mineral-rich froth phase. Current practice involves the use of inorganic depressants, which are toxic and non-biodegradable. Environmentally friendly, flexible and affordable flotation depressants are needed due to the depletion of easy-to-process high-grade ores as well as sustainability and environmental concerns. This paper discusses various organic depressants that have been adopted for selective depression of unwanted minerals in chalcopyrite flotation. The origin and chemistry, organic depressant-gangue minerals interaction mechanism, and the use of organic depressants in the most common chalcopyrite-flotation instances, including chalcopyrite separation from galena, molybdenite, sphalerite, pyrite, pyrrhotite, talc, serpentine and carbonaceous materials, are discussed. This review shows that organic depressants can partially or fully replace current inorganic depressants used in suppressing both sulfide and non-sulfide gangue minerals in chalcopyrite flotation. In this review, a well-detailed and well-referenced discussion is provided for the current state of organic depressants in chalcopyrite flotation, as well as a valuable discussion is provided to comparatively evaluate the depression performance of the various reported organic depressants. Finally, suggestions are made regarding future research challenges and directions. The recent advancements, developing features, and research prospects discussed in this article will provide a helpful reference for academics who want to delve deeper into the greening of chalcopyrite flotation process. [ABSTRACT FROM AUTHOR]

In this study, hydroxypropyltrimethyl ammonium chloride chitosan (HACC) was first introduced as a depressant during separating chalcopyrite from molybdenite (Cu-Mo). The selective effects of HACC on the separation of Cu-Mo were conducted by single-mineral flotation experiments. The findings from this study revealed that HACC helped separate Cu and Mo efficiently at pH 6 with 8 mg/dm3 of HACC, resulting in 76.22% and 5.38% of Mo and Cu flotation recovery, respectively. The adsorption mechanism of HACC was investigated via zeta potential, adsorption density, and contact angle measurement along with FT-IR and XPS analyses. The contact angle and adsorption density measurements offer indisputable proof that HACC can adsorb on the surface of chalcopyrite. Furthermore, FT-IR and XPS analyses confirm that N atoms in quaternary ammonium groups of HACC interact with Cu sites on the surface of chalcopyrite. The findings also suggest that HACC adsorbs on the surface without significantly impacting molybdenite. All these results confirm that HACC can be an effective chalcopyrite depressant. [ABSTRACT FROM AUTHOR]

Lithium‐ion capacitor (LIC) is a promising energy storage device, which combines double advantages of high‐energy lithium‐ion batteries (LIBs) and high‐power supercapacitors. However, the reported anode materials for LICs are synthesized based on the high‐purity chemicals under complicated and time‐consuming conditions, which exhibit a prohibitive cost in practical application. Herein, natural molybdenite is employed as the precursor to construct a high‐capacity and low‐cost anode material of LICs. Specifically, molybdenite is exfoliated into thin‐layer MoS2 under the interaction of hydrazine hydrate and sodium hydroxide, and then coupled with reduced graphene oxide to form a MoS2@rGO composite. Resulting from high reactive activity and structural stability, the MoS2@rGO anode shows excellent lithium‐ion storage performance including high specific capacity (936 mAh g−1 at 100 mA g−1) and rate capability (446 mAh g−1 at 5000 mA g−1). By using MoS2@rGO as an anode and activated carbon as a cathode, the assembled LIC device provides a maximum energy density of 105 Wh kg−1. Even at a high power density of 25 000 W kg−1, the energy density is still up to 65 Wh kg−1. This work provides a reference for the commercial utilization of natural molybdenum resources in the energy storage field. [ABSTRACT FROM AUTHOR]

The Hongyuan porphyry Mo–Cu deposit (PMCD) is a rare example of a "reduced" deposit, in contrast to classical oxidized porphyry Cu or Mo–Cu deposits. It is characterized by an ilmenite–series I–type felsic granitoid intrusion, reduced ore‐forming fluids with methane‐rich fluid inclusions, and widely distributed primary pyrrhotite. Mo–Cu mineralization in the Hongyuan PMCD occurs as disseminated in porphyry, granular in miarolitic cavity, and vein‐type in the quartz vein. These three types of mineralization are generally produced in the late magmatic period, magmatic‐hydrothermal transition period, and hydrothermal period, respectively. Molybdenite from miarolitic cavities shows a greater contribution from mantle fluid, as evidenced by mantle He proportions of 37.6%–16.8%. Molybdenite in quartz veins has relatively lower mantle He proportions of 1.63%–10.5%, indicating a predominantly crustal fluid source. The 3He/4He variations of these two groups of molybdenite illustrate an increasing input of crustal fluid during the magmatic to hydrothermal transition. Molybdenite samples from miarolitic cavities and quartz veins yield a Re‐Os model age of 300.5 ± 3.7 Ma, which is consistent with the U–Pb ages of zircons in the wallrock porphyries (300–302 Ma). This further indicates simultaneous diagenesis accompanied by mineralization. The Sr–Nd isotopic compositions (initial 87Sr/86Sr: 0.703404–0.703552; initial 143Nd/144Nd: 0.512585–0.512655; εNd[t]: +6.56 to +7.90) and young T2DM model ages (421–531 Ma) of the Hongyuan porphyries suggest that these rocks were derived from partial melting of the basaltic lower crust. We propose that mantle‐derived fluids rose up and mixed with fluids from the lower crust under an extensional tectonic setting, forming mantle‐like Sr–Nd–He–Ar isotopic compositions. The pre‐mineralization stage of the Hongyuan reduced PMCD is marked by quartz‐molybdenite ± K‐feldspar ± pyrite veins or veinlets and miarolitic cavities in the intensively potassic alteration zone. These veins formed at high temperatures (400–476°C) and high salinities (47.5–56.6 wt.%). The syn‐mineralization stage is the main metallogenic stage represented by numerous quartz‐molybdenite ± pyrrhotite veins associated with moderate to high temperatures (248°C–424°C) and low to high salinities (1.57–50.1 wt.%). The post‐mineralization stage is characterized by low temperatures (104–270°C) and low salinities (0.35–8.81 wt.%). Fluid immiscibility, mixing with meteoric water, ore fluid‐wall rock interactions, and decreasing temperature and salinity have played important roles during molybdenum mineralization. [ABSTRACT FROM AUTHOR]

The Hannivka molybdenum deposit is located in the northeastern side of the Kryvyi Rih structure, within the East Hannivka monocline. Molybdenum mineralization is confined to the contact zone of granitoids of the Demuryne complex with metabasites of the Novokryvorizka suite. The main volume of molybdenum mineralization is concentrated in the exocontact, in metabasites, and only 10-15% in endocontact granitoids. The molybdenum-bearing zone is represented by schistose, moderately quartzized and biotitized fine-grained metabasalts, which contain quartz, epidote-quartz, epidote, sometimes feldspar-quartz veins and veinlets and moderate (0.5-3%) sulfide mineralization. The volume of vein material ranges from 0.5 to 3-5%. The geological-morphological type of mineralization is defined as linear stockwork. Leading processes responsible for the development of molybdenite are quartzization and biotitization, namely silicic-alkaline metasomatism. Using JSM-6700F і JXСА-733 electron microscopes, the following ore minerals have been diagnosed and studied: magnetite, ilmenite, molybdenite, loellingite, arsenopyrite, pyrrhotite, pyrite, chalcopyrite, sphalerite. Based on their structural positions and relationships, several successive ore stages have been identified: early oxide (ilmenite-magnetite), main sulfide with molybdenite, potentially gold-bearing arsenide-sulfoarsenide-sulfide and late sulfide. Molybdenite is localized in zalbands of thin (1-3 mm, occasionally up to 2 cm) quartz veinlets, sometimes in the form of boudinaged structures, lenses and pockets reaching sizes up to 4 cm, as well as in host metabasalts and plagiogranites. Conditionally, three morphological types of molybdenite can be distinguished: a) medium-sized elongated tabular, platy, and foliated crystals ranging in size from 0.1 mm to 1.5-2 mm, which are oriented subparallel to the vein structures and rock foliation; b) fine-grained (from 10-20 µm to 0.1 mm) elongated flakes uniformly or randomly oriented; c) isometric crystals of hexagonaltabular habitus with sizes ranging from 0.1 to 0.7 mm. Outlined are several areas that require further investigation: epitaxial growths of molybdenite and silicates and the conditions of their formation, the time of formation of molybdenite and ore-generating granitoids. [ABSTRACT FROM AUTHOR]

In the flotation separation process of a Cu-Mo-W polymetallic ore, the wastewater from the scheelite cleaning flowsheet contains large numbers of residual flocculants and metal ions, and the separation of chalcopyrite and molybdenite requires a large number of environmentally harmful depressants. Therefore, it is necessary to find new methods to reduce the environmental and cost pressures of wastewater treatment and the use of depressants. In this work, the flotation wastewater from the scheelite cleaning flowsheet for the separation of chalcopyrite and molybdenite by selective surface passivation was investigated for the first time. Flotations of single minerals and artificially mixed minerals with or without immersion pretreatment in the presence and absence of aeration were performed. The results showed that pulp pH had no effect on the flotation of either mineral, and a molybdenite recovery of 93.22% with a chalcopyrite recovery of 10.77% was achieved under the conditions of 10 days of immersion pretreatment with aeration, 350 mg/L of kerosene, and 100 mg/L of MIBC. By combining the electrochemical cyclic voltammetry analysis and characterization by XRD and SEM, the selective surface passivation mechanism of chalcopyrite was discussed, which could be due to the coverage of the insoluble oxidation products, especially jarosite. This work has simultaneously achieved the depressant-free flotation separation of molybdenite and chalcopyrite and the reuse of scheelite flotation wastewater, which is of great significance for environmental protection and cost saving.

There are magnetic dillerences between chalcopyrite and molybdenite, so they can be separated by high gradient magnetic separation theoretically, and the particle size and particle size distribution ol material have signilicant ellect on the high gradient magnetic separation ellicient lor chalcopyrite and molybdenite. During this investigation, the capture characteristics ol rod matrix to chalcopyrite with dilierent particle size was analyzed, and the experiment of separating pure mineral mixture ol chalcopyrite and molybdenite with dillerent size was carried out by pulsating high gradient magnetic separation. Besides, the perlormance ol pulsating high-gradient magnetic separation lor actual copper-molybdenum mixed concentrate alter classification and at lull grain size was carried out The results showed that: the pulsating high-gradient magnetic separation showed poor recovery lor line-grained chalcopyrite, and the mechanical clogging ol line molybdenite in magnetic capture products was obviously more serious than that ol coarse molybdenite・ Pulsating high-gradient magnetic separation lor the classified coppermolybdenum mixed concentrate showed signilicantly better copper-molybdenum separation perlormance than the copper-molybdenum separation at lull grain size. Alter classifying the copper molybdenum mixed concentrate into two particle sizes ol + 0. 025 mm and 一 0. 025 mm, pulsating high gradient magnetic separation experiments were carried out under optimal conditions. The copper recovery rate ol the copper concentrate obtained was 55. 36%, the Cu and Mo grades were 30. 86% and 0. 067 %, respectively, and the Mo recovery rate of the molybdenum concentrate was 91. 72%. This research is ol significance to guide the industrial application ol pulsating high gradient magnetic separation of copper and molybdenum. [ABSTRACT FROM AUTHOR]

The Lower Urgen molybdenum deposit (44,856 t Mo @ 0.141%), situated in the northern Great Xing'an Range, is a newly discovered porphyry molybdenum deposit. Mineralization is characterized by veinlet-disseminated- and vein-type quartz–sulfide orebodies primarily occurring in the cupola of the Early Cretaceous granite porphyry stock. In this study, we present a detailed description of the ore geology, molybdenite Re-Os dating, H-O-S-Pb isotopic compositions, and fluid inclusion (FI) analyses including petrography, laser Raman, and microthermometry to precisely constrain the timing of ore formation, the origin of ore-forming fluids and materials, as well as the metal precipitation mechanism. Molybdenite Re-Os dating yielded two model ages of 141.2 ± 1.5 and 147.7 ± 1.7 Ma, coeval with the regional Late Jurassic–Early Cretaceous molybdenum metallogenesis. The hydrothermal process can be divided into three stages: the quartz–molybdenite(–pyrite) stage, quartz–polymetallic sulfide stage, and quartz–carbonate stage. Four types of FIs were distinguished for quartz, including two-phase liquid-rich (L-type), saline (S-type), CO2-rich (C1-type), and CO2-bearing (C2-type) FIs. Microthermometric data showed that the homogenization temperatures and salinities from the early to late stages were 240–430 °C, 5.0–11.9, and 30.1–50.8 wt% NaCl equiv.; 180–280 °C and 3.0–9.1 wt% NaCl equiv.; and 120–220 °C and 0.2–7.9 wt% NaCl equiv., respectively, suggesting a decreasing trend. H-O isotopic compositions indicate that the ore-forming fluids were initially of magmatic origin with the increasing incorporation of meteoric water. S-Pb isotopic compositions indicate that the ore-forming materials originated from granitic magmas, and the mineralization is genetically related to the ore-bearing granite porphyry stock in the deposit. Fluid immiscibility and fluid–rock interaction are collectively responsible for the massive deposition of molybdenite in stage 1, whereas fluid mixing and immiscibility played a critical role in the deposition of polymetallic sulfide in stage 2. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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.)

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources 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 process mineralogy of a copper-molybdenum mixed concentrate in Tibet was studied by means of chemical analysis， microscopic analysis and MLA analysis. The research shows that the mixed concentrate contains 19.00% copper and 0.38% molybdenum， and both copper and molybdenum mainly exist in the form of sulfide. Pyrite， chalcopyrite and bornite are the main minerals in the mixed concentrate， with molybdenite present at a content of 1.0%.The grinding fineness of the mixed concentrate is extremely fine， and the degree of dissociation of molybdenite is excellent. Additionally， a small part of molybdenite exists in coexistence with chalcopyrite and pyrite. The research results provide theoretical guidance for on-site copper-molybdenum separation and transformation. [ABSTRACT FROM AUTHOR]

The optical and electrical properties of monolayer MoS2 and MoS2 adsorbed with chlorine under uniaxial strain is investigated by using DFT-D2 Grimme approach. As a result of mechanical strain, bandgap of semiconducting monolayer MoS2 and chlorine adsorbed MoS2 decreases (in a zig-zag manner), which leads to transition from direct to indirect bandgap material and a semiconductor to metal transition. The red shift mechanism, in which the absorption peak relocated to the lower energy regions of electromagnetic spectrum, was seen in MoS2 structures subjected to strains of 0.6%, 0.8%, and 1% and also in Cl adsorbed MoS2 structures subjected to strains of 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, and 1%. Blue shift phenomenon is observed in the remaining strained structures of MoS2 where the applied values of strain are 0.1%, 0.2% and 0.4%, causing the absorption peaks to shift towards the higher energy values. By application of uniaxial strain on all the structures, absorption boost as well as spread over the entire visible spectrum (380–780 nm) and a very limited absorption is observed in UV band (below 350 nm). There is a good correlation between dielectric constant and refractive index of all adsorbed nanostructures. Additionally, all strained structures are highly efficient across the visible spectrum, making them ideal for optoelectronics and solar harvesting. [ABSTRACT FROM AUTHOR]

Rhenium, a unique and valuable metal with exceptional properties which is vital in various industrial applications, primarily found in conjunction with minerals like molybdenite and chalcopyrite, predominantly in western countries. Despite its rarity, understanding its geological distribution, geochemical characteristics, atomic structure, and behavior is essential. This paper provides a concise overview of the geological and geographical occurrences of rhenium, shedding light on its formation within both igneous and sedimentary environments. Additionally, it examines its economic significance, emphasizing its critical role in industries like aerospace, electronics, and petrochemicals due to its high-temperature resistance, corrosion resistance, and electrical conductivity enhancement. This comprehensive exploration highlights the importance of rhenium as a byproduct of mining, contributing significantly to technological advancements and innovation across various sectors. [ABSTRACT FROM AUTHOR]

In order to optimize the recovery index ol molybdenite in the magnetized water system, a single-mineral Ilotation test ol molybdenite was conducted by orthogonal experiment, and the sensitivity relationship between the recovery ol molybdenite and the inlluencing lactors ol magnetization modilication in water was analyzed by BP neural network. The results showed that the sensitivity ol molybdenite recovery to dilierent magnetization lactors during Ilotation was in descending order: current frequency, demagnetization time, magnetization time, interaction between current frequency and magnetization time, and interaction between current frequency and demagnetization time. The study used the three main inlluencing lactors such as magnetic induction strength to predict the recovery ol molybdenum by the BP neural network action model, which had a good lit and accuracy, with a good lit jR2 ol 0. 970 4 and a relative average error ol only 1. 27%, and the model can be better used for the prediction ol the recovery ol molybdenite. The study has some relerence significance lor the industrial application ol using magnetized water to improve the Ilotation effect ol metal sullide ores. [ABSTRACT FROM AUTHOR]

Life on Earth depends on N2‐fixing microbes to make ammonia from atmospheric N2 gas by the nitrogenase enzyme. Most nitrogenases use Mo as a cofactor; however, V and Fe are also possible. N2 fixation was once believed to have evolved during the Archean‐Proterozoic times using Fe as a cofactor. However, δ15N values of paleo‐ocean sediments suggest Mo and V cofactors despite their low concentrations in the paleo‐oceans. This apparent paradox is based on an untested assumption that only soluble metals are bioavailable. In this study, laboratory experiments were performed to test the bioavailability of mineral‐associated trace metals to a model N2‐fixing bacterium Azotobacter vinelandii. N2 fixation was observed when Mo in molybdenite, V in cavansite, and Fe in ferrihydrite were used as the sole sources of cofactors, but the rate of N2 fixation was greatly reduced. A physical separation between minerals and cells further reduced the rate of N2 fixation. Biochemical assays detected five siderophores, including aminochelin, azotochelin, azotobactin, protochelin, and vibrioferrin, as possible chelators to extract metals from minerals. The results of this study demonstrate that mineral‐associated trace metals are bioavailable as cofactors of nitrogenases to support N2 fixation in those environments that lack soluble trace metals and may offer a partial answer to the paradox. [ABSTRACT FROM AUTHOR]

Organic depressants have low selectivity in separating molybdenite and talc because their metal sites lack activity for organics chemisorption. In this study, surface modification by copper sulfate was used to induce the differential adsorption of pectin onto molybdenite and talc surfaces for enhanced flotation separation. Contact-angle experiments, scanning electron microscopy, adsorption measurements, time-of-flight secondary-ion mass spectrometry, and X-ray photoelectron spectroscopy analyses were conducted to reveal the interaction mechanism. Results illustrated that molybdenite and talc could not be separated using pectin alone, while molybdenite was selectively depressed after surface modification by copper sulfate and this effect was strengthened under alkaline conditions. Metal sites (Mg, Si and Mo) of talc and molybdenite themselves were unable to react with pectin, whereas Cu+ would deposit and further function as active site for pectin chemisorption after surface modification. However, the quantity of deposited Cu sites dropped on talc surface and increased on molybdenite surface with increased pH, and the Mo atoms of molybdenite crystal were activated to take part in pectin chemisorption. Therefore, more pectin was adhered on molybdenite surface, which imparted molybdenite stronger wettability. Herein, surface-modification through metal ions can enable the differential adsorption of organic depressants and enhance the flotation separation of minerals.

A copper-molybdenum ore in Qinghai contains 0.084% Mo and 0.067% Cu. Process mineralogical study shows that molybdenum in the ore mainly exists in the form of molybdenite, while copper in the form of chalcopyrite, chalcocite and bornite. Based on the molybdenum ore property, the flowsheet of selective flotation was adopted．Copper and molybdenum were comprehensively recovered by flotation process. Under the condition of grinding fineness of 74 μm 70%, molybdenum concentrate was obtained by one roughing, one scavenging and two blank cleaning. After regrinding, molybdenum concentrate with molybdenum grade of 50.21% and recovery of 85.21% was obtained by three cleaning. After molybdenum flotation tailings were activated with copper sulfate, copper concentrate with grade of 15.32% and recovery of 54.92% was obtained by one roughing, one scavenging and four cleaning. The comprehensive recovery of valuable elements was realized.

In recent years, transition metal dichalcogenides have received great attention since they can be prepared as two‐dimensional semiconductors, presenting heterodesmic structures incorporating strong in‐plane covalent bonds and weak out‐of‐plane interactions, with an easy cleavage/exfoliation in single or multiple layers. In this context, molybdenite, the mineralogical name of molybdenum disulfide, MoS2, has drawn much attention because of its very promising physical properties for optoelectronic applications, in particular a band gap that can be tailored with the material's thickness, optical absorption in the visible region and strong light–matter interactions due to the planar exciton confinement effect. Despite this wide interest and the numerous experimental and theoretical articles in the literature, these report on just one or two specific features of bulk and layered MoS2 and sometimes provide conflicting results. For these reasons, presented here is a thorough theoretical analysis of the different aspects of bulk, monolayer and bilayer MoS2 within the density functional theory (DFT) framework and with the DFT‐D3 correction to account for long‐range interactions. The crystal chemistry, stiffness, and electronic, dielectric/optical and phonon properties of single‐layered, bilayered and bulk molybdenite have been investigated, to obtain a consistent and detailed set of data and to assess the variations and cross correlation from the bulk to single‐ and double‐layer units. The simulations show the indirect–direct transition of the band gap (K–K′ in the first Brillouin zone) from the bulk to the single‐layer structure, which however reverts to an indirect transition when a bilayer is considered. In general, the optical properties are in good agreement with previous experimental measurements using spectroscopic ellipsometry and reflectivity, and with preliminary theoretical simulations. [ABSTRACT FROM AUTHOR]

A simple, rapid, cost‐effective and non‐enzymatic amperometric sensor for sensitive and simultaneous determination of uric acid (UA), dopamine (DA), and ascorbic acid (AA) was developed based on a new combination of carbon black (CB) and molybdenite (MLN) modified glassy carbon electrode (GCE). The synergistic effect of CB and MLN can increase electrode's conductivity, accelerate the electrochemical catalytic reaction and enhance the oxidation currents of UA, DA and AA. Cyclic voltammetry demonstrated the sensor to perform excellently in the electrochemical oxidation of AA, DA and UA, respectively. The oxidation potentials are well separated (oxidation peaks at −50 mV, 200 mV and 350 mV vs. Ag/AgCl) for AA, DA and UA with the detection limits of 5 μmol/L, 8.7 μmol/L and 9 μmol/L (S/N=3), respectively. The MLN‐CB/GCE sensor also demonstrated superior electrochemical properties including good stability, selectivity and reproducibility. In addition, the prepared sensor for UA allowed the determination of UA in highly diluted body fluids (urine), and the analytical results obtained by the present sensor were in good agreement with those obtained by conventional spectrophotometry. [ABSTRACT FROM AUTHOR]

Background. The kinetics of the oxidation of molybdenite concentrate in sodium hypochlorite solutions was previously studied. It was of interest to compare it with the behavior of pyrite concentrate under the same conditions. Purpose: to study the kinetics of oxidative leaching of gold and silver from pyrite concentrate, in hypochlorite electrolyte, using the rotating disk method. Methodology. Pyrite concentrate of Almalyk MMC JSC was used, pressed into tablet discs18 mm; sodium hypochlorite, controlled Au(I), Ag(I) in solutions (ААС Perkin-Elmer 3030В, ICP-Agilent 7500 IСP MS); solid phase SEM-EDS EVO-MA (Carl Zeiss, Instrum) and JCM-6000 Neoscope II (Jeol, Japan); FTIR Nicolet iS50 (Thermo Scientific, USA), XRD Empyrean (PANalytical). Originality. The parameters of the kinetic equation for the process of oxidative leaching: Au(I), Ag(I) from pyrite concentrate are obtained, the activation energy of the process of diffusion of Au, Ag from the solid into the liquid phase is calculated. Findings. Dependences of the leaching rate of Au, Ag from minerals in a hypochlorite electrolyte on a number of factors are constructed using the rotating disk method. [ABSTRACT FROM AUTHOR]