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Copper extraction techniques refers to the methods for obtaining copper from its ores. The conversion of copper consists of a series of chemical, physical, and electrochemical processes. Methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors. As in all mining operations, the ore must usually be beneficiated (concentrated). To do this, the ore is crushed. Then it must be roasted to convert sulfides to oxides, which are smelted to produce matte. Finally, it undergoes various refining processes, the final one being electrolysis. For economic and environmental reasons, many of the byproducts of extraction are reclaimed. Sulfur dioxide gas, for example, is captured and turned into sulfuric acid — which is then used in the extraction process. ==History== The earliest evidence of cold-hammering of native copper comes from the excavation at Çaÿonü Tepesi in eastern Anatolia. The radiocarbon date is 7250 ± 250 BCE. Among the various items considered to be votive or amulets there was one that looked like a fishhook and one like an awl. Pločnik archaeological site in southeastern Europe (Serbia) contains the oldest securely dated evidence of copper making at high temperature, from 5,500 BCE. The find in June 2010 extends for additional 500 years the earlier record of copper smelting from Rudna Glava (Serbia), dated to 6th millenium BCE. Copper smelting technology gave rise to the Copper Age and then the Bronze Age. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Copper extraction techniques」の詳細全文を読む スポンサード リンク
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