Molybdenum deposition

The five types of molybdenum deposits include (i) molybdenum and copper porphyry deposits (ii) Quartz vein and pipes (iii) Pegmatites and apatites dikes (iv) Contact-meta-morphic rocks and tactite bodies of silica bearing limestone and (v) Sedimentary rocks containing bedded deposits. 

The organic deposition sources are made of a variety of materials including ceramics (e.g., boron nitride, aluminum oxide, and quartz) or metallic boats (e.g., tantalum or molybdenum). Deposition is carried out in high vacuum at a base pressure of around 10-7 torr. The vacuum conditions under which OLEDs are fabricated are extremely important [41] and evaporation rates, monitored using quartz oscillators, are typically in the range 0.01 0.5 nm/s in research and development tools. In manufacturing, higher rates or multiple sources may be used to reduce tact times. 

Geochemistry and tectonics as an exploration tool for Circum-Pacific porphyry copper, gold, and molybdenum deposits evidence from the... 

Perello, J.A., Fleming, J.A., O Kane, K.P., Burt, P.D., Clarke, G.A., Himes, M.D., Reeves, A.T. 1995. Porphyry copper-gold-molybdenum deposits in the Island Copper cluster, northern Vancouver Island, British Columbia. In Schroeter, T.G. (ed.). Porphyry Deposits of the Northwestern Cordillera of North America. Canadian Institute of Mining, Metallurgy and Petroleum, Special Volume 46, 214-238. 

The Mount Pleasant Mine Property is located in Charlotte County, southwestern New Brunswick, Canada. The mineralization is divided into two main groups consisting of porphyry-type tungsten-molybdenum deposits, and vein and replacement-type tin polymetallic bodies. The deposits at Mount Pleasant are described in some detail in Kooiman et al. (1986) and Sinclair et al. (2006). Their petrogenetic character is discussed in Yang et al. (2003), Inverno Hutchinson (2006) and Sinclair et al. (2007). 

Figure 9.10 AFM images of molybdenum deposits obtained at 493 K from [Mo(CO)6] sublimed at 303 K on (a) Si02/Si and (b) (0001) a-alumina.

Molybdenum nitride itself has been dispersed on platinum clusters dispersed in EMT zeolite. In this study, coverage of platinum particles by molybdenum deposition was investigated and was reported to suppress the activity for benzene hydrogenation and enhance the heptane conversion. With respect to bare Pt for heptane conversion, the aromatisation activity was reduced, whereas isomerisation and hydrogenolysis were observed. 

Fig. 11. STM images 4035Ax4090A of molybdenum deposited on the Au(l 11) surface at room temperature and under UHV conditions. The inset (890Ax920A) shows the location in the bulged elbows of the herringbone reconstruction of 20-A wide molybdenum nanoclusters.

Thin soils underlain by limestone can also be the source of false anomalies. On a traverse across a molybdenum deposit at Tongsban, Jiangsu province, which is covered by 0.3-1.0 m of eluvium, CO2 anomalies were found not only above the ore body but also on a nearby ridge. Here soils are particularly thin and poorly developed, and the underlying limestone creates an environment in which the pH can be as high as 8.5, allowing carbonate enrichment which in turn produces a false anomaly of CO2. 

Traverses were made across four copper-molybdenum deposits and soil gas was collected from holes drilled to a depth of 1.0-1.8 m. The soil air was analysed titrimetrically after absorption in an iodine solution. Control analyses were performed by mass spectrometry. The ore deposits, with widths of between 10-400 m, are associated with skams and granite porphyries. The thickness of the overburden is between 0.6-3 m. The ore minerals are principally chalcopyrite, molybdenite, chalcocite, bomite, galena, sphalerite, magnetite and pyrite. Weathering and secondary enrichment have affected the ores to a maximum depth of 95 m. 

Fig. 13-5. Mercury content of soil over the Tongshan copper-molybdenum deposit. Profile I.

Fig. 13-8. Profile of Hg content of soil over the Zhangyan copper-molybdenum deposit.

Mierenshan, China, 444 Copper-gold-uranium deposits Olympic Dam, Australia, 331 Copper-molybdenum deposits Skam... 

Sakhalinsk, Russia, 462 Molybdenum deposits, 440, 450 See also Copper-molybdenum deposits... 

Zhangyan, China, 443 Copper-molybdenum deposits Tongshan, China, 441, 443, 444 Zhangyan, China, 446 Polymetallic deposits, 443 Xiaomaoshan, China, 442,445 Stratiform deposits Base-metal deposits... 

Quite recently attention was paid to the role of oxides, either as electro-active species, as impurities or as additives in the electro-deposition of transition metals. This may be demonstrated, e.g. in the case of electro-deposition of molybdenum, where the electrolysis of neither pure K2M0O4, nor the KF-K2M0O4 mixture yields a molybdenum deposit. However, introducing small amounts of boron oxide, or silicon dioxide to the basic melts, smooth and adherent molybdenum deposits may be obtained. Also, in the case of niobium and tantalum deposition, the presence of oxygen either from the moisture or added on purpose leads to the formation of oxohalo-complexes, which due to their lowered symmetry and thus lower energetic state, decompose easier at the cathode yielding pure metal. 

From the literature it follows that the electro-deposition of molybdenum from the binary MeF-Me2Mo04 mixtures is impossible. However, a small addition (1 mole %) of boron oxide or Si02 to the electrolyte facilitates the electro-deposition of molybdenum. The presence of boron or silicon oxide most probably modifies the structure of the melt, which results in changes in the cathode process. The survey of electrochemistry of molybdenum deposition was given by Danbk et al. (1997). 

Such heteropolyanions are rather voluminous and thus, much more polarizable. In the vicinity of the cathode in the electric double layer, this anion is strongly polarized and finally disintegrated into smaller species, from which consecutive molybdenum deposition takes place. The X-ray diffraction analysis of the solid deposit on the top closure and furnace wall proved that the deposit consists of pure K2SiF6, which supports the assumption on the formation of the above-mentioned heteropolyanions. Unfortunately, the authors did not study the mechanism of the cathodic process in this system. 

From the physico-chemical and thermodynamic analysis of the molten systems KF-K2M0O4-B2O3 and KF-K2Mo04-Si02, it can be concluded that the formation of heteropolymolybdates containing boron, [BM06O24] , and silicon, [SiMo 12040]" , as a central atom is most probably responsible for an easy molybdenum deposition. Besides, the entry of fluorine atoms into the coordination sphere of molybdenum in the heteropolyanions lowers the symmetry and thus, also the electrochemical stability of such electro-active species. 

While SNAM developed mixtures based on the use of bismuth and vanadium compounds, Montedison, whose exclusive operating license was acquired in 1975 by UOP, preferred a supported catalyst based on oxides of cerium, molybdenum and tellurium on silica. OSW employs a mixture of metallic bismuth and molybdenum deposited on a support... 

So CS, Rye DM, Shelton KL (1983) C, H, O, and S isotope and flnid inclnsion study of the Weolag Tungsten-Molybdenum Deposit, Korea Fluid histories of metamorphic and ore-forming evens. Eeon Geol 78 1551-1573... 

Besides the molybdenum minerals there are five genetic types of molybdenum deposits porphyry deposits contact-metamor-phic zones in intrusive granites quartz veins pegmatites and deposits bedded in sedimentary rocks. The first three types are of hydrothermal origin and provide almost all of the molybdenum currently mined. Currently, the porphyry deposits (range from 0.05 to 0.25% Mo) are of prime importance industrially, and are predominantly mined. Secondary copper-molybdenum porphyry deposits contain much lower molybdenum concentrations (0.01-0.05% Mo), so that molybdenum can only be recovered as a byproduct. 

Dolukhanova, N. I. (1960). An experiment in the application of hydrochemical survey to copper and molybdenum deposits in the Armenian S.S.R. IntemaL Geol. Rev. 2 20-42. 

Calculation of the isotopic composition of water in equilibrium with muscovite from the Climax molybdenum deposit, Colorado... 

Hall W.E., Friedman I. and Nash J.T., 1974, Fluid inclusion and light stable Isotope study of the Qimax molybdenum deposits, Colorado. Econ. GeoL, 69, 884—901. 

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