History

山西快乐十分开奖:History

The first utilization of manganese can be traced back to the Stone Age. Men were already using manganese dioxide as a pigment for their cave paintings during the upper paleolithic period, 17.000 years ago. Later in Ancient Greece, the presence of manganese in the iron ore used by the Spartans is a likely explanation as to why their steel weapons were superior to those of their enemies. Manganese has also long been related to glass-making. The Egyptians and the Romans used manganese ore either to decolorize glass or to give it pink, purple and black tints. Even today it is stll used for this purpose.

In the mid-17th century, the German chemist Glauber obtained permanganate, the first usable manganese salt. Nearly a century later, manganese oxide became the basis for the manufacture of chlorine. Yet manganese was only recognized as an element in 1771, by the Swedish chemist Scheele. It was isolated in 1774 by one of his collaborators, J.G. Gahn. At the beginning of the 19th century, both British and French scientists began considering the use of manganese in steelmaking, with patents granted in the U.K. in 1799 and 1808. In 1816, a German researcher observed that manganese increased the hardness of iron, without reducing its malleability or toughness.

In 1826 Prieger in Germany produced a ferromanganese containing 80% manganese in a crucible. J.M. Heath produced metallic manganese in England in about 1840. The following year, Pourcel began industrial-scale production of spiegeleisen, a pig-iron containing a high percentage of manganese, and in 1875 he started the commercial production of ferromanganese with a 65% manganese content. The major breakthrough in the use of manganese occurred in 1860. At that time, Sir Henry Bessemer was trying to develop the steelmaking process which was to bear his name. But he experienced difficulty with an excess of residual oxygen and sulphur in the steel. The problems were overcome thanks to the beneficial effect of manganese, disclosed in a patent granted to Robert Mushet in 1856. Mushet suggested adding spiegeleisen after the blow to introduce both manganese and carbon and remove oxygen. This procedure made the Bessemer process possible, and thus paved the way for the modern steel industry. Ten years later, in 1866, Sir William Siemens patented the use of ferro-manganese in steelmaking so as to control the levels of phosphorus and sulphur.

[history2] Subsequently, and in contrast to all the early work involving manganese and steelmaking, Leclanché in 1868 developed the dry cell battery. This uses manganese dioxide as a depolariser in a simple yet effective dry cell and the battery market today is the second largest consumer of manganese. The history of manganese in the 20th century has been a stream of new processes and metallurgical/ chemical applications developed with a significant impact on markets as diverse as beverage cans, agricultural pesticides and fungicides and electronic circuitry used in consumer products. Details of these applications are analysed later.

 


极速快乐十分是啥意思

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