Molybdenite

1) Specific fillers (layer-lattice solids) molybdenite or molysulfide (M0S2) and graphite. 

3) Less frequently used materials ceramics, for example, BN (boron nitride), aramid, or carbon fibers miscellaneous, for example, calcium fluoride, cerium fluoride, tungsten disulfide (WS2), mica, borax, silver sulfate, cadmium iodide, lead iodide, and talc. 

Among the above listed materials, M0S2 and graphite are the predominant solid lubricants. In dry powder form, these are effective lubricants due to their lamellar structures. The lamellae orient parallel to the surface in the direction of motion as 

Solid/dry lubricants are useful under conditions when conventional liquid lubricants are inadequate [3], namely high temperatures, conditions of reciprocating motion, and extreme contact pressures. 

Molybdenite or molybdenum disulfide (M0S2) or molysulfide is a mineral [5] found in granites, syenites, gneisses, and crystalline limestones. A NIOSH (National Institute for Occupational Safety and Health) web site [6] has listed a total of 31 synonyms for molybdenite. The use of molybdenite as a lubricant was apparently recorded in the early seventeenth century by John Andrew Cramer 7]. Chrysler, an automotive manufacturer, was the first to widely use M0S2 grease in the 1960s. 

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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. 

L. Rhenus, Rhine) Discovery of rhenium is generally attributed to Noddack, Tacke, and Berg, who announced in 1925 they had detected the element in platinum ore and columbite. They also found the element in gadolinite and molybdenite. By working up 660 kg of molybdenite in 1928 they were able to extract 1 g of rhenium. 

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... 

Another spherical, nonpolar molecule is methane its isotherms on both graphite and molybdenite at 77 K have a step-like character. Ethane, whilst slightly less symmetrical, is still nonpolar and it gives two distinct steps on cadmium at 97-4 K, the second step being nonhorizontal. ... 

Nokes reagent 1 complex mixture selective depressant in molybdenite circuits improves molybdenite grade... 

The functional group ia collectors for nonsulfide minerals is characterized by the presence of either a N (amines) or an O (carboxyUc acids, sulfonates, etc) as the donor atoms. In addition to these, straight hydrocarbons, such as fuel oil, diesel, kerosene, etc, are also used extensively either as auxiUary or secondary collectors, or as primary collectors for coal and molybdenite flotation. The chain length of the hydrocarbon group is generally short (2—8 C) for the sulfide collectors, and long (10—20 C) for nonsulfide collectors, because sulfides are generally more hydrophobic than most nonsulfide minerals (10). 

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. 

Most of the processing of the molybdenite by-product to obtain rhenium is carried out in the United States and Germany. Some Canadian concentrate is processed in the United States and returned to the owners in Canada for resale. 

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. 

CH=CH2, R=C4 g ) have been found to be particularly effective on molybdenite and copper—molybdenite ores. 

Molybdenite [1309-56 ] M0S2, normally floats with the copper sulfides. Therefore, the copper concentrate from the cleaner cells frequently has to be separated from molybdenite in a separate flotation circuit before the copper concentrate goes to the smelter. Gold, silver, selenium, and tellurium are collected with the copper concentrate. 

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). 

Test, m. test cupel test furnace cupella-tion furnace indicator graphite molybdenite. -asche, /. bone ash. -benzin, n. 

Data for which no reference is given are from the Slrukturbericht of P. P. Ewald and C. Hermann. 6 R. W. G. Wyckoff, Z. Krisl., 75,529 (1930). W. H. Zachariasen, ibid., 71, 501, 517 (1929). d The very small paramagnetic susceptibility of pyrite requires the presence of electron-pair bonds, eliminating an ionic structure Fe++S2. Angles are calculated for FeS2, for which the parameters have been most accurately determined. The parameter value (correct value = 0.371) and interatomic distances for molybdenite are incorrectly given in the Slrukturbericht. 

Trigonal-Prism Radii. In molybdenite and the corresponding tungsten sulfide the metal atom is surrounded by six sulfur atoms at the corners of a right trigonal prism of axial ratio unity, the bond orbitals involved being those discussed in an earlier section. Prom the observed interatomic distances the values 1.37 and 1.44 A are calculated for Mo and IPIV in such crystals (Table XV). 

The magnetic criterion is particularly valuable because it provides a basis for differentiating sharply between essentially ionic and essentially electron-pair bonds Experimental data have as yet been obtained for only a few of the interesting compounds, but these indicate that oxides and fluorides of most metals are ionic. Electron-pair bonds are formed by most of the transition elements with sulfur, selenium, tellurium, phosphorus, arsenic and antimony, as in the sulfide minerals (pyrite, molybdenite, skutterudite, etc.). The halogens other than fluorine form electron-pair bonds with metals of the palladium and platinum groups and sometimes, but not always, with iron-group metals. 

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