Copper is one of the earliest ancient metals discovered by human beings. As early as three thousand years ago, humans began to use copper. Copper in nature is divided into natural copper, copper oxide and copper sulfide. The reserves of natural copper and copper oxide are small. Now more than 80% of the world’s copper is refined from copper sulfide ore. The copper content of this ore is very low, generally about 2-3%. Copper, elemental symbol Cu, atomic weight 63.54, specific gravity 8.92, melting point 1083Co. Pure copper is a light rose or reddish color. Copper has many valuable physical and chemical properties, such as high thermal and electrical conductivity, strong chemical stability, high tensile strength, easy to weld, corrosion resistance, plasticity, ductility. Pure copper can be drawn into very fine copper wire, to make a very thin copper foil. It can form alloys with zinc, tin, lead, manganese, cobalt, nickel, aluminum, iron and other metals. The formed alloys are mainly divided into three categories: brass is copper zinc alloy, bronze is copper tin alloy, and white copper is copper cobalt nickel alloy. The development of copper metallurgy technology has experienced a long process, but the smelting of copper is still dominated by fire smelting, its output accounts for about 85% of the world’s total copper production, modern wet smelting technology is gradually promoted, is expected to reach 20% of the total output by the end of this century, the introduction of wet smelting has greatly reduced the smelting cost of copper.

Copper parts can be found in almost all machines. In addition to the large amount of steel used in motors, circuits, oil pressure systems, air pressure systems and control systems, a wide variety of transmission parts and fixed parts made of brass and bronze, such as gears, worm gear, worm, coupling parts, fasteners, twisting parts, screws, nuts, etc., are everywhere. Bearings or bushings made of reduced wear copper alloy are used between almost all parts in relative mechanical motion. In particular, the cylinder liner and slide plate of 10,000-ton large extruders, forging presses and presses are almost made of bronze, and the casting weight can reach several tons. Almost all of the elastic components are made of silicon bronze and tin bronze. Welding tools, die casting mold and so on can not be separated from copper alloy, and so on.