Large Molybdenum Research Articles

Magnetic Method Surveying and Its Application for the Concealed Ore-Bodies Prospecting of Laba Porphyry Molybdenum Ore Field in Shangri-La, Northwestern Yunnan Province, China

Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.

Further Studies of Ore-Forming Fluid Sources of Bangpu Molybdenum-Copper Polymetallic Deposit, Tibet

Bangpu molybdenum-copper polymetallic deposit is located in the eastern section of the Gangdese Porphyry Copper Belt of Tibet. It is a typical large porphyry molybdenum copper polymetallic deposit. The isotope study of fluid inclusions H and O in the quartz (calcite) of various mineralization stages shows that, the ore-forming fluid comes mainly from meteoric hydrothermal caused by atmospheric precipitation, which has consistency with ore-forming fluid sources of Gangdese Porphyry Copper Belt. The Mo-Cu phase with low δD value (-140.5 ~ -104.0 ) suggests a large-scale magmatic degassing. The alteration and mineralization have been caused precisely by the degassing, and the obvious O isotope drift occurred being accompanied by alteration-mineralization, so that the fluid has a low δ18O (vary from 5.50 to 9.0 ). The statistical research indicates that, the massive magmatic degassing occurred in Gangdese Porphyry Copper Belt, and was gradually increased from east to west, suggesting the direct impact of the magmatic degassing on the formation of the porphyry copper-gold deposit and molybdenum copper deposit: the stronger the magmatic degassing, the more easily to form the molybdenum-based porphyry deposit, otherwise it will be formed the deposits dominated by Cu and Au.

Large molybdenum isotope variations trace subsurface fluid migration along the Dead Sea transform

Large (−0.6‰ to +2.3‰) δ97/95Mo variations occur in molybdenum-enriched iron oxide veins located in anticlines adjacent to the Dead Sea transform, and are thought to reflect the solutions from which the veins formed because of efficient scavenging of Mo by iron oxides. The wide range of δ97/95Mo values occurs in a paleohydrologic setting in which dense, concentrated, evaporitic marine brines in the Dead Sea Rift valley (δ97/95Mo ~1.6‰) penetrated and interacted with sedimentary rocks of the rift flanks, which included Cretaceous bituminous chalks (δ97/95Mo 0.8‰–1.2‰), before intermixing with Fe-bearing groundwater containing molybdenum of igneous and clastic origin. The δ97/95Mo values higher than seawater (1.6‰–2.3‰) are attributed to Rayleigh isotopic fractionation along the path of the brine migration. Molybdenum isotopes thus reveal a powerful potential to trace the sources and processes governing subsurface metalliferous fluid migration.

A periplasmic aldehyde oxidoreductase represents the first molybdopterin cytosine dinucleotide cofactor containing molybdo‐flavoenzyme from Escherichia coli

Three DNA regions carrying genes encoding putative homologs of xanthine dehydrogenases were identified in Escherichia coli, named xdhABC, xdhD, and yagTSRQ. Here, we describe the purification and characterization of gene products of the yagTSRQ operon, a molybdenum-containing iron-sulfur flavoprotein from E. coli, which is located in the periplasm. The 135 kDa enzyme comprised a noncovalent (alpha beta gamma) heterotrimer with a large (78.1 kDa) molybdenum cofactor (Moco)-containing YagR subunit, a medium (33.9 kDa) FAD-containing YagS subunit, and a small (21.0 kDa) 2 x [2Fe2S]-containing YagT subunit. YagQ is not a subunit of the mature enzyme, and the protein is expected to be involved in Moco modification and insertion into YagTSR. Analysis of the form of Moco present in YagTSR revealed the presence of the molybdopterin cytosine dinucleotide cofactor. Two different [2Fe2S] clusters, typical for this class of enzyme, were identified by EPR. YagTSR represents the first example of a molybdopterin cytosine dinucleotide-containing protein in E. coli. Kinetic characterization of the enzyme revealed that YagTSR converts a broad spectrum of aldehydes, with a preference for aromatic aldehydes. Ferredoxin instead of NAD(+) or molecular oxygen was used as terminal electron acceptor. Complete growth inhibition of E. coli cells devoid of genes from the yagTSRQ operon was observed by the addition of cinnamaldehyde to a low-pH medium. This finding shows that YagTSR might have a role in the detoxification of aromatic aldehydes for E. coli under certain growth conditions.

Effect of molybdenum on hardness of low-temperature plasma carburized austenitic stainless steel

The effect of molybdenum in hardening on low-temperature plasma carburized layer of austenitic stainless steel was investigated. This compared a low-temperature carburized layer of AISI 316 (Fe–17Cr–10Ni–2Mo) with that of AISI 304 (Fe–18Cr–8Ni) to evaluate the influence of molybdenum on carburizing. Samples were plasma carburized using DC plasma apparatus under 667 Pa of mixed gas flow of 5% CH 4 + 45% H 2 + 50% Ar at 673 K or 723 K for various durations. Depth profiles of hardness and micro-structural layer thickness were measured; GDOES, TEM, and XRD were subsequently used to characterize their microstructures. Surface hardness of 316 steel carburized at 673 K for 8 h reached 800 HK, but that of 304 steel remained at 530 HK. Results show no carbide formation in either steel treated at 673 K. The degree of lattice expansion by carburizing in the presence of molybdenum, 316 steel, is higher than that of 304 steel. Furthermore, the diffusion rate of carbon in the 316 steel is higher than that in the 304 steel. The higher hardness of carburized 316 steel is inferred to result from carbon super saturation enhanced by the effect of large molybdenum atoms, which can widen the octahedral sites.

Exposure of metal mirrors in the scrape-off layer of TEXTOR

Large molybdenum mirrors have been exposed in the SOL of TEXTOR in order to simulate conditions relevant for ITER optical components. Distortions of the reflectivity – increase as well as decrease – are found in the erosion and deposition dominated areas, respectively. The changes are most pronounced in the near UV and level off in the IR and can partly be attributed to observed surface changes. A novel periscope system was installed and mirrors exposed in a pilot experiment to simulate the transmission of light to distant sensors in ITER.

Interface characterization between large area freestanding diamond films and molybdenum substrates

A study of an interfacial layers between freestanding diamond films and substrate diamond film growth was performed. Polycrystalline diamond films were grown on molybdenum substrates by dc arc jet plasma methods. A molybdenum carbide layer epitaxially was formed on the substrates used several times later, and its structure and composition were analyzed by different characterization techniques. The concentration of carbon decreased with an increase of distance from the substrate surface. Thicker and better-defined interfacial layers were found in diamond films grown on substrates used several times. This interface efficiently avoided carbon and hydrogen diffusion and also improved the chemical bond between diamond film and substrate during diamond growth. Characterization by X-ray diffraction, Raman spectroscopy and SEM analysis were also carried out.

Growth of chemical vapour deposition diamond on large molybdenum cylinders for crossed-field amplifier applications

Growth of chemical vapour deposition diamond on large molybdenum cylinders for crossed-field amplifier applications

Improved substrate temperature stability during molecular beam epitaxy growth using indium free mounting of small substrates of various shapes

Large substrate surface temperature decreases are observed during molecular beam epitaxy growth onto small indium bonded substrates, due to coating of the molybdenum block. These large temperature transients, along with other difficulties associated with indium bonding (e.g., potential substrate surface damage, unwanted indium on the back of the substrate) make indium free substrate mounting desirable, however, indium free mounting systems have previously been restricted to whole standard‐sized round wafers. In this study we compare the temperature characteristics of new indium free modular substrate mounting blocks, which can accommodate substrates of various sizes (up to 3 inch diameter) and shapes, with traditional indium mounting of small substrates. Although the new modular indium free holders have a large molybdenum surface area exposed to the molecular beams, we find that the substrate surface temperature transients during growth are reduced to nearly negligible levels versus similar growth on indium bonded substrates, due to the effective thermal isolation of the substrate from the molybdenum. The real effects of these temperature differences observed by in situ pyrometry were confirmed by ex situ deep level transient spectroscopy (DLTS) measurements of homoepitaxial GaAs films, which show a two‐to‐three order of magnitude trap density increase in films grown on indium bonded substrates versus films grown on substrates mounted without indium bonding. This DLTS result is consistent with a real growth temperature difference between the two mounting techniques as was measured in situ by pyrometry.

Re-Os Isotope ages of molybdenum deposits in East Qinling and their significance

Dating of metallic ore deposits has been one of the problems concerned with by ore geologists for many years. The establishment of the Re-Os Isotope Laboratory at the Institute of Rock and Mineral Analysis, Chinese Academy of Geological Sciences, has provided us with a new technique to carry out geochronological studies of molybdenum ores. As one of the most important Re-bearing minerals, molybdenite contains almost no common osmium, but187Os was derived completely from decay of187Re, with187Os content as the function of Re content in the mineral. An ID-ICP-MS technique has been used in this study, and Re-Os isotopic ages of several large molybdenum deposits of different types from the East Qinling molybdenum belt have been determined. It is indicated that the Huanglongpu carbonatite vein-type molybdenum-(lead) deposit has a Re-Os age corresponding to Indosinian, while the rest porphyry-type molybdenum deposits and porphyry-skarn-type molybdenum-(tungsten) deposits have Re-Os ages corresponding to Yenshanian.

Strengthening in a DS casting Ni3Al base alloy IC6

A unidirectionally solidified casting γ′ base alloy IC6, with the chemical composition (at.%) 16.3–17.6% Al, 8.0–8.3% Mo, 0.16–0.78% B, Ni balance has been developed for advanced gas turbine blades and vanes. The experimental results show that this alloy has high yield strengths from room temperature to 1100°C, excellent creep resistance at temperatures up to 1100°C. The microstructural observations and analysis indicate that the superior mechanical properties of this alloy may be attributed to solid solution hardening by the large molybdenum addition, second phase strengthening by γ′ phase and other minor phases that precipitate in various temperature ranges, the formation of a γ raft structure during creep, and to the existence of high density misfit dislocation networks at γ′/γ interface areas due to a high value of γ′/γ misfit.

Microstructure/mechanical property relationship in a DS Cast Ni3Al-base alloy

A Ni-Al-Mo directionally solidified (DS) casting γ-base superalloy, with the chemical composition (wt%) 7.5 to 8.5% Ni, 10 to 14% Al, Mo ≤0.15% B, has been developed for advanced gas turbine blades and vanes. The mechanical properties of this alloy have been determined by tensile tests at room temperature and in the temperature range 700 to 1000 °C and by stress-rupture tests in the temperature range 760 to 1100 °C. The microstructures of the as-cast and homogenized specimens and of specimens after creep de-formation at 1000 to 1100 °C have been examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and optical microscopy techniques. The results show that this alloy has a high yield strength from room temperature up to 1100 °C, excellent creep resistance at temperatures up to 1100 °C, as well as a lower density and higher melting point than currently available nickel superal-loys. The microstructural observations and analysis indicate that the superior mechanical properties of this alloy may be attributed to solid solution hardening by the large molybdenum addition, second-phase strengthening by y phase and other minor phases that precipitate in various temperature ranges, the for-mation of a γ raft structure during creep, and to the existence of high-density misfit dislocation networks at γ / γ interface areas due to a high value of γ / γ misfit.

Petrology, composition, and age of intrusive rocks associated with the Quartz Hill molybdenite deposit, southeastern Alaska

A large porphyry molybdenum deposit (Quartz Hill deposit) was recently discovered in the heart of the Coast Range batholithic complex about 70 km east of Ketchikan, southeastern Alaska. Intrusive rocks associated with the mineral deposit form two composite epizonal to hypabyssal stocks and many dikes in country rocks. The stocks are characterized by a variety of textural rock types varying from equigranular or weakly seriate biotite granite to porphyries with aphanitic or very fine grained and aplitic groundmasses. These rocks contain about equal amounts of quartz, albitic plagioclase, and microperthitic microcline and less than 2.5% biotite. Unaltered rocks contain between 0.2 and 1% CaO, less than 1.7% combined Fe2O3, FeO, and MgO, and 74.4 to 77.7% SiO2. Total alkalis are between 8 and 9%, and K2O/Na2O is about 1.1. The range of major-oxide variation is small, but it is systematically related to lithology. Many trace-elements, including B, Pb, Sn, and Li have low concentrations. Intrusive rocks associated with the Quartz Hill deposit are more albitic and possibly trace-element depleted compared to some other rocks associated with porphyry molybdenum deposits.All observed metallization and alteration is within the Quartz Hill stock. Molybdenite forms fracture coatings and occurs in veins with quartz. Alteration is widespread and includes development of secondary quartz, pyrite, K-feldspar, biotite, white mica, chlorite, and zeolite. Field relations indicate that the stocks were emplaced after regional uplift and erosion of the Coast Range batholithic complex, and K–Ar data show that intrusion and alteration took place in late Oligocene time, about 27 to 30 Ma ago. Data from the Ketchikan quadrangle indicate that porphyry molybdenum metallization in the Coast Range batholithic complex is associated with regionally extensive but spotty, middle Tertiary or younger, felsic magmatism.

Molybdenum and Tungsten in the Caucasus

IT is announced by “Russia Today” Press Service that large molybdenum and tungsten works have been opened recently in Kabardino-Balkaria, in the Caucasian mountains. The plant is situated at the foot of Mount Tyrny-Auz. Soviet geologists began to prospect for ores on this mountain in 1934. At an altitude of 9,850 ft. they discovered large deposits of rich molybdenum and tungsten ores. Owing to the situation of the Tyrny-Auz deposits, however, the extraction of the ores has presented a difficult problem, and local weather is severe. Everything about the workings is mechanized. The ore, which is extracted by means of electric drills, is brought away from the face by electric trains, sent to the surface by conveyer belt and lowered to the works at the foot of the mountain by cable hoists. The ore mine has four electric power stations and a central air-compressing station. There is an electric sub-station underground. The nearest centre to the new works is Nalchik, capital of Kabardino-Balkaria.