Copper is a transition element, chemical symbol Cu, English copper, atomic number 29. Pure copper is a soft metal. The surface is freshly cut red and orange with metallic luster. Ductility, thermal conductivity and conductivity are high, so the most commonly used materials, such as cables and electrical components, are also used as building materials, which can form many kinds of alloys. Copper alloys have excellent mechanical properties and low resistivity, the most important of which are bronze and brass. In addition, copper is also a durable metal that can be recycled without compromising its mechanical properties.
Bivalent copper salt is the most common copper compounds, the hydrated ion is blue, and chloride ligand is green, is the source of azurite and turquoise minerals such as color, was widely used as a pigment in history. Copper green (alkali carbonate) is produced when the copper structure is corroded. Decorative arts mainly use copper and copper pigments.
Copper is one of the earliest metals used by man. As early as prehistoric times, people began to excavate open copper mines and use the copper to make weapons, tools and other utensils, and the use of copper had a profound effect on the progress of early human civilization. Copper is a metal found in the earth's crust and oceans. Copper has a content of about 0.01% in the crust, and copper in individual copper deposits can reach 3% to 5%. Copper, in nature, is mostly found in compounds called copper ores. Copper has a weak activity, and copper and copper sulfate can be replaced by copper. Copper is not soluble in non - oxidized acid.
Purpose: copper is related very closely to human and non-ferrous metal, is widely used in electrical, light industry, machinery manufacturing, construction industry, defense industry and other fields, in China the consumption of non-ferrous metal materials after aluminum. Copper is a kind of red metal and is also a kind of green metal. It is green metal, mainly because it has a low melting point and easy to melt and smelt again, so recycling is quite cheap. The ancient times were mainly used for the casting of utensils, art and weapons, and the more famous vessels and works of art such as the smother and the four sheep.
Transport is the third-largest market for copper, about 13 per cent of the total, roughly the same as in the 1960s. Although the importance of transportation has not changed, the use of copper has changed greatly. For many years, automatic radiators were the most important end users in this area; However, the use of copper in automatic electronics and electronics has grown rapidly, while the use of the heat exchanger market has declined. The average life of a car is 10-15 years, and almost all of the copper (including radiators and wiring) is recovered and recycled in its entirety.
Industrial machinery and equipment
Industrial machinery and equipment are another major application market, in which copper tends to have long service life. COINS and arms are the main end users in this area. Bullets are rarely recovered, some COINS can be melted, and many are kept by collectors or savers and cannot be recycled.  in the manufacture of machinery and transport vehicles, it is used to manufacture industrial valves and fittings, instruments, sliding bearings, molds, heat exchangers and pumps.