Molybdenite Molybdenum

Yu and Bailey (1992) studied the reaction of nitrobenzene with four sulfide minerals under anaerobic conditions. Observed half-lives of nitrobenzene were 7.5, 40, 105, and 360 h for the reaction with sodium sulfide, alabandite (manganese sulfide), sphalerite (zinc sulfide), and molybdenite (molybdenum sulfide), respectively. Aniline and elemental sulfur were found as reduction products of nitrobenzene-manganese sulfide reaction. Aniline was also a reduction product in the nitrobenzene-molybdenum sulfide and nitrobenzene-sodium sulfide reactions. Several unidentified products formed in the reaction of nitrobenzene and sphalerite (Yu and Bailey, 1992). 

Molybdenum and its uses. Molybdenite, molybdenum trioxide, ammonium molybdate. Wolfram (tungsten) and its uses. Scheelite, CaWO, and wolframite, (Fe,Mn)W04. Wolfram carbide. Uranium and its ores pitchblende, car-notite. Sodium diuranate, uranyl nitrate. Nuclear fission. 

CAS 1317-33-5 EINECS/ELINCS 215-263-9 Synonyms Molybdenite Molybdenum sulfide Molybdenum (IV) sulfide Molybdic sulfide... 

Molybdenum (V) chloride. See Molybdenum pentachloride Molybdenum disulfide CAS 1317-33-5 EINECS/ELINCS 215-263-9 Synonyms Molybdenite Molybdenum sulfide Molybdenum (IV) sulfide Molybdic sulfide Definition Molybdenite is the natural mineral form Empirical M0S2... 

The molybdenum story is not rich in events. It is even trivial. Only one detail is of interest this rare element was discovered very early, namely, in 1778, when the chemical analysis was just coming of age. Molybdenum was first separated in the form of oxide. The name molybdenum had appeared long before the new element was discovered. It originates from the Greek names molybdena for a lead mineral (lead glance) and molybdos for lead , the two resembling each other. There was another mineral which also resembled these two very much later it became known as molybdenite (molybdenum sulphide). 

There are many molybdenum-containing minerals in nature but only one of them, molybdenite, molybdenum disulfide, MoSj (Figures M36 and M37) has any economic importance. Typically, molybdenite occurs in an environment of silica-rich intrusive rocks, consolidated from magma beneath the surface of the earth. 

Gr. molybdos, lead) Before Scheele recognized molybdenite as a distinct ore of a new element in 1778, it was confused with graphite and lead ore. The metal was prepared as an impure form in 1782 by Hjelm. Molybdenum does not occur native, but is obtained principally from molybdenite. Wulfenite, and Powellite are also minor commercial ores. 

Moissanite, see Silicon carbide Molybdenite, see Molybdenum disulfide Molybdite, see Molybdenum(VI) oxide Molysite, see Iron(III) chloride Montroydite, see Mercury(II) oxide Morenosite, see Nickel sulfate 7-water Mosaic gold, see Tin disulfide Muriatic acid, see Hydrogen chloride, aqueous solutions... 

Molybdenite concentrate contains about 90% M0S2. The remainder is primarily siUca, with lesser amounts of Fe, Al, and Cu. The concentrate is roasted to convert the sulfide to technical molybdic oxide. Molybdenum is added to steel in the form of this oxide. In modem molybdenum conversion plants, the oxidized sulfur formed by roasting M0S2 is converted to sulfuric acid. 

A small portion of molybdenite concentrate production is purified to yield lubricant-grade molybdenum disulfide, a widely used soHd-state lubricant. 

Before scmbbing procedures were estabUshed for copper ore, most of the rhenium was lost as the volatile (Re202). A small portion, perhaps 10%, was retained in flue dust, which was processed to give the metal. A commercial flotation (qv) process for the recovery of the molybdenite by-product is available that permits a high recovery of molybdenum and rhenium. This process is used at the Caridad copper mine in Mexico. 

The most important ore of molybdenum is the sulphide molybdenite, M0S2, of which the largest known deposit is in Colorado, USA, but it is also found in Canada and Chile. Less important ores are wulfenite, PbMo04, and powellite, Ca(Mo,W)04. 

Molybdau-kies, m. molybdenite, -ocker, m. molybdic ocher, molybdite. -oxyd, n. molybdenum oxide (specif., one higher than MojOa). -oxydul, n. molybdous oxide (MoO, also MojOa). 

Chromium(III) sulfide, CrySs chromium selenide, CrSe chromium(III) telluride, Cr2Tc3 molybdenum(IV) sulfide, M0S2 (molybdenite) molybde-num(IV) selenide, MoSe2 molybdenum(IV) telluride, MoTey tungsten(IV) sulfide,... 

T ike metals minerals also exhibit typical crystalline structures. As an example, the structure of molybdenite is shown in Figure 1.17. It is hexagonal with six-pole symmetry and contains two molecules per unit cell. Each sulfur atom is equidistant from three molybdenum atoms and each molybdenum atom is surrounded by six sulfur atoms located at the comers of a trigonal prism. There are two types of bonds that can be established between the atoms which constitute the molybdenite crystal stmcture. They are the covalent bonds between sulfur and molybdenum atoms and the Van der Waals bonds between sulfur-sulfur atoms. The Van der Waals bond is considerably weaker than the covalent sulfur-molybdenum bond. This causes the bonds of sulfur-sulfur to cleave easily, imparting to molybdenite the property of being a dry lubricant. Molybdenite adheres to metallic surfaces with the development of a molecular bond and the friction between metallic surfaces is replaced by easy friction between two layers of sulfur atoms. 

Molybdenum is not found naturally in its elemental form. It is obtained primarily from the mineral molybdenite (MoS2), which contains an average 59.9% of molybdenum. It is the only source of molybdenum which accounts for most of the world s molybdenum supply. Processing flowsheet of molybdenum from this commercial source into principal commercial forms is illustrative of the wide and diverse applications of molybdenum and its chemicals (Figure 1.19). 

As a specific illustration reference may be drawn to molybdenum reserve scenario in the United States. The reserves are mainly grouped under five categories (i) primary, (ii) byproduct of copper ores, (iii) co-product of copper-molybdenum ores, (iv) by-product of tungsten ores, and (v) by-product of uranium ores. These have been presented and briefly elaborated in Table 1.14. It may finally be recorded by way of summary that the present day molybdenum sources in the world today seem to be principally of two main kinds first, the large-tonnage, low-grade, disseminated type of deposit in which molybdenite is the principal economic mineral second, the deposits in which molybdenite occurs as a by-product in... 

Drawing reference to the flotation practice of molybdenite, it may in the first instance be pointed out that production of molybdenite by flotation results from the processing of primary molybdenum ores and copper porphyry ores in which molybdenite is recovered as a byproduct. This by-product accounts for about one-third of the total molybdenum production in the western world. 

Molybdenite is another sulfide ore amenable to processing by chlorination. The reaction between molybdenum disulfide and chlorine, i.e.,... 

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