Views: 14 Author: Site Editor Publish Time: 2015-06-09 Origin: TungstenChina
Molybdenum is a metallic, silvery-white element which is very stable chemically but it will react with acids. The physical characteristic that makes molybdenum unique is that it has a very high melting point, 4,730 degrees Fahrenheit. This is 2,000 degrees higher than the melting point of steel. It is 1,000 degrees higher than the melting temperature of most rocks.
Molybdenite (MoS2) is the major ore mineral for molybdenum. It is rarely found as crystals, but is commonly found as foliated masses that is in folia or layers, like the mineral mica. It is metallic gray, has a greasy feel, and is very soft at only 1 on Mohs' hardness scale. Its softness, metallic luster and gray color led scientists to mistakenly believe it was a lead mineral. Geologically, molybdenite forms in high-temperature environments such as in igneous rocks. Some molybdenite forms when igneous bodies contact rock and metamorphose, or change, the rock.
Molybdenum is also found in the mineral wulfenite (Pb (MoO4). Wulfenite forms colorful, bright orange, red, and yellow crystals. They can be blocky or so thin that they are transparent.
Molybdenum is a needed element in plants and animals. In plants, for example, the presence of molybdenum in certain enzymes allows the plant to absorb nitrogen. Soil that has no molybdenum at all cannot support plant life.
Molybdenite was named after the Greek word molybdos, which means lead, by Swedish chemist Carl William Scheele. Sheele's studies led him to the conclusion that this mineral did not contain lead, but some other element. The mineral scheelite (Ca (WO4, MoO4)) was named after Scheele for this discovery.
The most important ore source of molybdenum is the mineral molybdenite. A minor amount is recovered from the mineral wulfenite. Some molybdenum is also recovered as a by-product or co-product from copper mining. The leading producers of molybdenum are the United States, Canada, China, Chile, Mexico, Peru, Russia and Mongolia.
The two largest uses of molybdenum are as an alloy in stainless steels and in alloy steels-these two uses consume about 60% of the molybdenum needs in the United States. Stainless steels include the strength and corrosion-resistant requirements for water distribution systems, food handling equipment, chemical processing equipment, home, hospital, and laboratory requirements. Alloy steels include the stronger and tougher steels needed to make automotive parts, construction equipment, gas transmission pipes. Other major uses as an alloy include tool steels, for things like bearings, dies, machining components, cast irons, for steel mill rolls, auto parts, crusher parts, super alloys for use in furnace parts, gas turbine parts, and chemical processing equipment. Molybdenum also is an important material for the chemicals and lubricant industries. Moly has uses as catalysts, paint pigments, corrosion inhibitors, smoke and flame retardants, dry lubricant (molybdenum disulfide) on space vehicles and resistant to high loads and temperatures. As a pure metal, molybdenum is used because of its high melting temperatures (4,730 F) as filament supports in light bulbs, metal-working dies and furnace parts.
Molybdenum also is an important material for the chemicals and lubricant industries. Molybdenum has uses as catalysts, paint pigments, corrosion inhibitors, smoke and flame retardants, dry lubricant (molybdenum disulfide) on space vehicles and resistant to high loads and temperatures. As a pure metal, molybdenum is used because of its high melting temperatures as filament supports in light bulbs, metal-working dies and furnace parts. Molybdenum cathodes are used in special electrical applications. It can also be used as a catalyst in some chemical applications.