Metallurgy

1. Metallurgy Naturally occurring metals tend to be heterogeneous, which means that various elements can be found in the material.  These impurities that occur in natural metals can be separated from the material by melting the metal at its melting point.  By heating the material to its melting point, the unwanted material will separate from the desired metal and will also make the material malleable.  Malleablility is how easily a material's shape can be changed by applying pressure, usually through hammering. Annealing Annealing is the process of heating and reheating metals to a high temperature to reduce the stresses that occurred in the material.  When metal is heated and then allowed to cool, it becomes more malleable and easier to manipulate it into a desired shape.  After the impurities in desired material have been removed through the use of heat the material can be heated to a point where it becomes molten. The molten copper can be poured into precut molds to make tools such as axes, plows, jewelry, and other desired objects. Smelting Smelting, the process of separating metal from other impurities present in it, began possibly around 4,000 B.C. in Africa. [1] By smelting material its strength and malleability is greatly increased. To separate metals from other materials, the material has to be heated to a high temperature and could only be exposed to so much oxygen during this process otherwise the desired material would not be produced.Sources: [1] Herbert, Eugenie W. 1984 Red Gold of Africa. Madison: University of Wisconsin. (p. 4) [2] Mohen, Jean Pierre and Christiane Eluere. 2000 The Bronze Age in Europe. New Tork: Harry N. Abrams, INC. Publishers. (p. 28) Written by Alex Boyce, 2003 http://www.mnsu.edu/emuseum/history/trade/metalinanhist.htm http://www.azcu.org/teachersOut4.php Bronze smelting furnace at the Archäologisches FreilichtMuseum (AFM) Oerlinghausen (DE)

2. Smelting requires a high degree of knowledge. The technique of smelting was not just a chance discovery made by early humans. Removing the impurities from copper, while giving the material enough oxygen, and heating the material to a high temperature required careful planning and a great deal of skill. Smelting cannot be done over an open campfire it had to be done in an enclosed fire, a potter’s kiln. A kiln is an enclosed furnace used to heat clay until it hardens and can be used in the smelting of metal. The kiln is used for smelting in order to keep as much oxygen out as possible and to heat the copper to a high temperature to melt the metal.  The smelting of lead and copper led to the discovery of iron. The Iron Age began in 2000 BC in Asia Minor. Iron working began in Iran sometime around 1500-1000 BC and slowly spread to the rest of the Mediterranean. The period between the 4,000 B.C. and 2,000 B.C. is known as the Chalcolithic Period.  During the Chalcolithic period humans experimented with metallurgy, mostly working with gold, copper, and tin.  But the first evidence of humans manipulating metals predates the Chalcolitihic era. At sites in Iran and Turkey, there has been evidence found that humans were experimenting with metallurgy as far back as 8,000 B.C.[2] Sources: [1] Herbert, Eugenie W. 1984 Red Gold of Africa. Madison: University of Wisconsin. (p. 4) [2] Mohen, Jean Pierre and Christiane Eluere. 2000 The Bronze Age in Europe. New Tork: Harry N. Abrams, INC. Publishers. (p. 28) Written by Alex Boyce, 2003 http://www.mnsu.edu/emuseum/history/trade/metalinanhist.htm These ancient techniques worked well and the methods used out lasted the bronze age.  The Romans also used the same techniques at other copper mines and many European mines continued to use them through out the middle ages. http://fluffle-valve.co.uk/joomla/index.php?option=com_content&task=view&id=22&Itemid=42

3. Smelting was used as well to make bronze, an alloy. Alloys are mixtures of metals. Bronze is an alloy of copper and tin.  Smelting was accomplished initially in an open fire. A hole one to two feet in diameter was dug in the ground. The hole was lined with fire-resistant clay or stone. Charcoal was placed in a layer on top of the clay, then was covered by copper ore. Charcoal burns particularly hot, raising temperatures enough to melt the copper. The charcoal also releases gases that react with the copper minerals to reduce them to copper metal. A molten mass of the dense copper formed, topped by lighter waste products, or slag. When the mass was cool, the brittle, glassy slag could be broken off, leaving a cake of refined copper behind. The furnace in this method is called an open hearth. Remnants of open hearths have been found in Sumerian ruins.  A more complex method used the crucible, a ceramic pot into which the charcoal and copper ore were placed. The crucible was placed into a fireplace, or furnace. Bellows, often made of goat skins, directed a draft of air to raise the temperature. The copper cake produced by this method was cleaner than that in the open hearth. Copper ingots were cast into the shape of bars, rings, and other shapes suitable to be transported to Sumerian cities.  http://www.unr.edu/sb204/geology/smelt.html

4. Guangxi has been praised as the "base camp" of bronze drums and in Guangxi Sheng Bowuguan (Guangxi Provincial Museum), there is an exhibition hall (on ground floor) solely dedicated to these prized collection of ancient bronze drums. Bronze drums are the representative cultural relics of ancient ethnic groups of South China. In ancient time, bronze drums were taken as a symbol of power and wealth, as a sacred vessel used in religious service and entertainment http://www.gochinaadventure.com/public/ebbs/disbbs.asp?BoardID=1&ID=27&replyID=27 Bronze coins http://www.collectorsinternet.com/AncientCoins/ancientbronze.htm Ancient Celtic-Scythian (Sarmatian) Bronze Socketed Javelin Point (Lapel Pin/Brooch). Fifth Century B.C. http://www.susu-saaa.org/art/celtic/47542.php Chinese pu vessel with interlaced dragon design, Spring and Autumn Period (722 BC-481 BC) http://upload.wikimedia.org/wikipedia/commons/f/f0/Pu_with_openwork_interlaced_dragons_design.jpg http://www.museums.norfolk.gov.uk/img/br00104.jpg

5. Metal casting http://www.mk-technology.com/geschichtemetallguss.html?&L=2

6. Metal casting http://www.mk-technology.com/geschichtemetallguss.html?&L=2