Learn About Copper

Copper is a ductile and malleable base metal that is valued for its high thermal and electrical conductivity. Easily identifiable because of its iridescent, golden red color, copper and its alloys, have been used by humans for thousands of years.

Due to its effectiveness as an electrical conductor, copper is now most often found in related applications, including in the wiring for our homes and offices, and in the circuitry, connectors, and components that make virtually all electronic devices function.

• Characteristics
• History
• Production
• ASTM Designations
• Prices
• Applications

Characteristics

Pure copper is a bright reddish-brown metal that, when exposed to corrosive environments, can take on a green-hued patina. This green layer of copper sulfate (or copper carbonate) results from a chemical process caused by alkalis, ammonia, sulfate compounds and acidic rainwater.

While patina on copper is an indication of corrosion, it works to protect the metal from further deterioration. For this reason, copper and copper alloys are often used in marine and architectural applications.

History

Copper is considered to be one of the first metals to be used by humans. The main reason for its early discovery and use is that copper can naturally occur in relatively pure forms.

Although various copper tools and decorative items dating back as early as 9,000 BC have been discovered, archaeological evidence suggests that it was the early Mesopotamians who, around 5000 to 6000 years ago, were the first to fully harness the ability to extract and work with copper.

Lacking modern knowledge of metallurgy, early societies, including the Mesopotamians, Egyptians and Native Americans, prized the metal mostly for its aesthetic qualities, using it like gold and silver for producing decorative items and ornaments.

Production

Copper is typically extracted from oxide and sulfide ores that contain between 0.5 and 2.0 percent copper. The refining techniques employed by copper producers depend on the ore type, as well as other economic and environmental factors. Currently, about 80 percent of global copper production is extracted from sulfide sources.

Regardless of the ore type, the mined copper ore must first be concentrated to remove gangue, unwanted materials embedded in the ore. The first step in this process is crushing and powderizing ore in a ball or rod mill. Virtually all sulfide-type copper ores, including chalcocite (Cu₂S), chalcopyrite (CuFeS₂) and covellite (CuS), are treated by smelting.

After crushing the ore to a fine powder, it is then concentrated by froth flotation, which requires mixing the powdered ore with reagents that combine with the copper to make it hydrophobic. The mixture is then bathed in water along with a foaming agent, which encourages frothing. 

Applications

From common household electrical wiring to boat propellers and from photovoltaic cells to saxophones, copper and its alloys are employed in a myriad of end-uses. In fact, the metal's use in a wide-range of core industries has resulted in the investment community turning to copper prices as an indicator of overall economic health, spurring the moniker 'Dr. Copper'.

To better understand copper's various applications, the Copper Development Association (CDA) has categorized them into four end-use sectors: electrical, construction, transport and other. The percentage of global copper production consumed by each sector is estimated by the CDA to be:

• Electrical 65%
• Construction 25%
• Transport 7%
• Other 3%

Aside from silver, copper is the most effective conductor of electricity. This, combined with its corrosion resistance, ductility, malleability, and ability to work within a wide range of power networks, makes the metal ideal for electrical wiring. 

Sources

European Copper Institute. Applications.
URL: http://copperalliance.eu/
The Copper Development Association Inc. Applications
URL: https://www.copper.org/applications/
Schoolscience.co.uk. Copper - A Vital Element. Copper Mining.
URL: http://resources.schoolscience.co.uk/cda/14-16/cumining/copch2pg2.html