Relative Abrasiveness of Materials

The purpose of the study was to assess this material as a potential source for lubricant grade molybdenum disulphide, because of the steady increase in its use in lubricants. However, the total consumption for lubricant use represents less than 4% of the primary molybdenite production. It seems unlikely, therefore, that the demand will justify even the low quoted cost of upgrading the by-product material, except where the availability of the indigenous source is important. 

Between 40% and 50% of the roasted concentrate is converted to ferromolybdenum, either by means of an electric furnace or by a thermite process. The thermite process involves ignition of a mixture of the roasted concentrate with aluminium and an iron source (iron ore and ferrosilicon) together with a flux. The resulting ferromolybdenum contains between 55% and 70% of molybdenum, and is used in alloy steel and cast iron manufacture. Some of the roasted concentrate is converted to briquettes by pressing with a pitch binder. The briquettes, weighing about 5 kg., are also used in manufacture of alloy steels and cast irons. 

Purified molybdic oxide is produced by volatilisation in a stream of air in sand-hearth furnaces at about 1200°C. Molybdic oxide melts at 795°C, but its vapour pressure is very high, and the volatilisation process is sometimes referred to as sublimation rather than distillation. The product is a fine powder containing from 99.5% to 99.97% of molybdenum trioxide. 

Ammonium molybdate is manufactured by dissolving technical molybdic oxide in hot ammonia. It can be highly purified to over 99.9% purity, and 

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Table 2.4 Relative Abrasiveness of Materials (Data from Ref.33)...

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