Manganese is a chemical element that is designated by the symbol Mn and has an atomic number of 25. Manganese (Mn) is a gray-white to silvery metal with a moderate melting temperature and relatively high specific gravity (7.2 to 7.4). It is found as the free element in nature (often in combination with iron), and in many minerals. The free element is a metal with important industrial metal alloy uses. In steel, manganese improves rolling and forging qualities, strength, toughness, stiffness, wear resistance, hardness, and hardenability.Manganese ions are variously colored, and are used industrially as pigments and as oxidation chemicals. Manganese (II) ions function as cofactors for a number of enzymes; the element is thus a required trace mineral for all known living organisms.Manganese occurs principally as pyrolusite (MnO2), braunite, (Mn2+Mn3+6SiO12), psilomelane (Ba(Mn2+)(Mn4+)8O16(OH)4), and to a lesser extent as rhodochrosite (MnCO3). The metal is obtained by reduction of the oxide with sodium, magnesium, aluminum, or by electrolysis. Land-based resources are large but irregularly distributed. Over 80% of the known world manganese resources are found in South Africa and Ukraine. Other important manganese deposits are in China, Australia, Brazil, Gabon, India, Mexico and Indonesia.Manganese minerals are widely distributed; oxides, silicates, and carbonates are the most common. The discovery of large quantities of manganese nodules on the floor of the oceans may become a source of manganese. These nodules contain about 24% manganese, together with many other elements in lesser abundance.
Manganese is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking component, has accounted for most manganese demand, presently in the range of 85% to 90% of the total demand. Among a variety of other uses, manganese is a key component of low-cost stainless steel formulations and certain widely used aluminium alloys.
Manganese metal is ferromagnetic only after special treatment. The pure metal exists in four allotropic forms. The alpha form is stable at ordinary temperature; gamma manganese, which changes to alpha at ordinary temperatures, is said to be flexible, soft, easily cut, and capable of being bent.
The dioxide (pyrolusite) is used as a depolarizer in dry cells, and is used to "decolorize" glass that is colored green by impurities of iron. Manganese by itself colors glass an amethyst color, and is responsible for the color of true amethyst. The dioxide is also used in the preparation of oxygen and chlorine, and in drying black paints. The permanganate is a powerful oxidizing agent and is used in quantitative analysis and in medicine.
Trace amounts of manganese are very important to good health. It makes bones strong yet flexible, and it aids the body in absorbing Vitamin B1. It also is an important activator for the body to use enzymes. As little as 0.00002% Mn in the human body is essential. Studies have shown that a lack of manganese leads to infertility in animals.
Manganese (Mn) is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking component, accounts for most domestic manganese demand, presently in the range of 85% to 90% of the total. Manganese ferroalloys, consisting of various grades of ferromanganese and silicomanganese, are used to provide most of this key ingredient to steelmaking. Products for construction, machinery, and transportation are leading end uses of manganese. Manganese also is a key component of certain widely used aluminum alloys and, in oxide form, dry cell batteries. As ore, additional quantities of manganese are used for such nonmetallurgical purposes as plant fertilizers, animal feed, and colorants for brick.
Manganese combined with other elements is widely distributed in the Earth’s crust. The most important ores consist primarily of manganese dioxide (MnO2) in the form of pyrolusite, romanechite, and wad. Manganese is essential to plant growth and is involved in the reduction of nitrates in green plants and algae. It is an essential trace element in higher animals, in which it participates in the action of many enzymes. Lack of manganese causes testicular atrophy. An excess of this element in plants and animals is toxic.
More than 95 percent of the manganese produced is used in the form of ferromanganese and silicomanganese alloys for iron and steel manufacture. Manganese ores containing iron oxides are first reduced in blast furnaces or electric furnaces with carbon to yield ferromanganese, which in turn is used in steelmaking. Adding manganese, which has a greater affinity for sulfur than does iron, converts the low-melting iron sulfide in steel to high-melting manganese sulfide. Produced without manganese, steel breaks up when hot-rolled or forged. Steels generally contain less than 1 percent manganese. Manganese steel, also called Hadfield steel, is used for very rugged service; containing 12–14 percent manganese, it provides a hard, wear-resistant, and self-renewing surface over a tough unbreakable core. Pure manganese produced electrolytically is used mostly in the preparation of nonferrous alloys of copper, aluminum, magnesium, and nickel and in the production of high-purity chemicals. Practically all commercial alloys of aluminum and magnesium contain manganese to improve corrosion resistance and mechanical properties.
The principal industrial compounds of manganese include several oxides. Manganous oxide, or manganese monoxide, MnO, is used as a starting material for the production of manganous salts, as an additive in fertilizers, and as a reagent in textile printing. It occurs in nature as the green mineral manganosite. It also can be prepared commercially by heating manganese carbonate in the absence of air or by passing hydrogen or carbon monoxide over manganese dioxide.
Total world production of manganese alloys reached 11.8 million metric tons, up by 14% from 2005. As in past years, manganese alloy production was dominated by China, producing approximately 42% (4.9 million mt). All other regions of the world showed marked increases in production except Japan and the Americas, which saw decreases of 15% and 18% respectively.
Chinese measures to control production and consolidate the industry continued with the the implementation of a 10% export tax on manganese alloys. They have also applied strict licensing regulations, having approved roughly 200 ferroalloy producers. Non-approved producers will face higher energy prices, through the use of a discriminatory energy tarriff. These measures are meant to reduce overcapacity, with current utilization estimated to be at only 48%.
Preliminary data (gross weight) for November 2007 indicate that consumption of manganese or containing 35% or more manganese, exclusive of that consumed at oron and steel plant, was 23,800 metric tons(t), according to U.S. Geological Survey, this was a 20% decrease from that in October 2007.
Coresponding industry stocks of ore at the end of November 2007 were 101,00 t, which was a 12% decrease from those at the end of October 2007. These data include estimates for annual respondents on the basic of 2006 data.
Manganese is a chemical element that is designated by the symbol Mn and has an atomic number of 25. Manganese (Mn) is a gray-white to silvery metal with a moderate melting temperature and relatively high specific gravity (7.2 to 7.4). It is found as the free element in nature (often in combination with iron), and in many minerals. The free element is a metal with important industrial metal alloy uses. In steel, manganese improves rolling and forging qualities, strength, toughness, stiffness, wear resistance, hardness, and hardenability.Manganese ions are variously colored, and are used industrially as pigments and as oxidation chemicals. Manganese (II) ions function as cofactors for a number of enzymes; the element is thus a required trace mineral for all known living organisms.Manganese occurs principally as pyrolusite (MnO2), braunite, (Mn2+Mn3+6SiO12), psilomelane (Ba(Mn2+)(Mn4+)8O16(OH)4), and to a lesser extent as rhodochrosite (MnCO3). The metal is obtained by reduction of the oxide with sodium, magnesium, aluminum, or by electrolysis. Land-based resources are large but irregularly distributed. Over 80% of the known world manganese resources are found in South Africa and Ukraine. Other important manganese deposits are in China, Australia, Brazil, Gabon, India, Mexico and Indonesia.
Manganese minerals are widely distributed; oxides, silicates, and carbonates are the most common. The discovery of large quantities of manganese nodules on the floor of the oceans may become a source of manganese. These nodules contain about 24% manganese, together with many other elements in lesser abundance.
Manganese is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking component, has accounted for most manganese demand, presently in the range of 85% to 90% of the total demand. Among a variety of other uses, manganese is a key component of low-cost stainless steel formulations and certain widely used aluminium alloys.
Manganese metal is ferromagnetic only after special treatment. The pure metal exists in four allotropic forms. The alpha form is stable at ordinary temperature; gamma manganese, which changes to alpha at ordinary temperatures, is said to be flexible, soft, easily cut, and capable of being bent.
The dioxide (pyrolusite) is used as a depolarizer in dry cells, and is used to "decolorize" glass that is colored green by impurities of iron. Manganese by itself colors glass an amethyst color, and is responsible for the color of true amethyst. The dioxide is also used in the preparation of oxygen and chlorine, and in drying black paints. The permanganate is a powerful oxidizing agent and is used in quantitative analysis and in medicine.
Trace amounts of manganese are very important to good health. It makes bones strong yet flexible, and it aids the body in absorbing Vitamin B1. It also is an important activator for the body to use enzymes. As little as 0.00002% Mn in the human body is essential. Studies have shown that a lack of manganese leads to infertility in animals.
Manganese (Mn) is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Steelmaking, including its ironmaking component, accounts for most domestic manganese demand, presently in the range of 85% to 90% of the total. Manganese ferroalloys, consisting of various grades of ferromanganese and silicomanganese, are used to provide most of this key ingredient to steelmaking. Products for construction, machinery, and transportation are leading end uses of manganese. Manganese also is a key component of certain widely used aluminum alloys and, in oxide form, dry cell batteries. As ore, additional quantities of manganese are used for such nonmetallurgical purposes as plant fertilizers, animal feed, and colorants for brick.
Manganese combined with other elements is widely distributed in the Earth’s crust. The most important ores consist primarily of manganese dioxide (MnO2) in the form of pyrolusite, romanechite, and wad. Manganese is essential to plant growth and is involved in the reduction of nitrates in green plants and algae. It is an essential trace element in higher animals, in which it participates in the action of many enzymes. Lack of manganese causes testicular atrophy. An excess of this element in plants and animals is toxic.
More than 95 percent of the manganese produced is used in the form of ferromanganese and silicomanganese alloys for iron and steel manufacture. Manganese ores containing iron oxides are first reduced in blast furnaces or electric furnaces with carbon to yield ferromanganese, which in turn is used in steelmaking. Adding manganese, which has a greater affinity for sulfur than does iron, converts the low-melting iron sulfide in steel to high-melting manganese sulfide. Produced without manganese, steel breaks up when hot-rolled or forged. Steels generally contain less than 1 percent manganese. Manganese steel, also called Hadfield steel, is used for very rugged service; containing 12–14 percent manganese, it provides a hard, wear-resistant, and self-renewing surface over a tough unbreakable core. Pure manganese produced electrolytically is used mostly in the preparation of nonferrous alloys of copper, aluminum, magnesium, and nickel and in the production of high-purity chemicals. Practically all commercial alloys of aluminum and magnesium contain manganese to improve corrosion resistance and mechanical properties.
The principal industrial compounds of manganese include several oxides. Manganous oxide, or manganese monoxide, MnO, is used as a starting material for the production of manganous salts, as an additive in fertilizers, and as a reagent in textile printing. It occurs in nature as the green mineral manganosite. It also can be prepared commercially by heating manganese carbonate in the absence of air or by passing hydrogen or carbon monoxide over manganese dioxide.
Total world production of manganese alloys reached 11.8 million metric tons, up by 14% from 2005. As in past years, manganese alloy production was dominated by China, producing approximately 42% (4.9 million mt). All other regions of the world showed marked increases in production except Japan and the Americas, which saw decreases of 15% and 18% respectively.
Chinese measures to control production and consolidate the industry continued with the the implementation of a 10% export tax on manganese alloys. They have also applied strict licensing regulations, having approved roughly 200 ferroalloy producers. Non-approved producers will face higher energy prices, through the use of a discriminatory energy tarriff. These measures are meant to reduce overcapacity, with current utilization estimated to be at only 48%.
Preliminary data (gross weight) for November 2007 indicate that consumption of manganese or containing 35% or more manganese, exclusive of that consumed at oron and steel plant, was 23,800 metric tons(t), according to U.S. Geological Survey, this was a 20% decrease from that in October 2007.
Coresponding industry stocks of ore at the end of November 2007 were 101,00 t, which was a 12% decrease from those at the end of October 2007. These data include estimates for annual respondents on the basic of 2006 data.
No comments:
Post a Comment