Copper

At the end of the refining process of ores (containing from 1 to 2% copper) the metal obtained – blister – is impure and contains between 98 and 99.5 % copper.

In order to get a highly pure copper, this blister is most often, dissolved electro-chemically and cast in anodes.

An electrolytic treatment turns these anodes into cathodes, which are then remelted according to different processes which create 3 main categories of copper :

• Copper CU-ETP (CuA1) – (Electrolytic tough-Pitch)
• Copper Cu-DHP (CuB1) – (Deoxydised High Residual Phosphorus)
• Copper Cu-OF     (CuC1) – ( Cu Oxygen Free)

Copper wires

The Cu-ETP whose conductivities (electrical & thermic) are particulary high has been chosen to make the copper wires used in electrotechnics.( pure silver is the only one to give better results).

It's an undeoxidized copper whose purity is 99.90%. It has been selected as a standard reference for the electrical conductivity (IACS : International Annealed Copper standard). It is said to be 100% IAC and is used to grade the conductivity of other metals (example nickel is 22% IACS, aluminium 63%, gold 70% and silver 106%).

Being very ductile, it gives by wiredrawing, extremely thin wires which can measure only 1/100 mm.
Finally, it resists fairly well to oxydation, which allows an easy soldering (tin).

The Cu-DHP is a copper deoxidized with phosphorus which permits a good welding (torch, etc ...) impossible with the Cu-ETP.
It doesn't have a very good electric conductivity (70 to 90 IACS) but it is easy to shape.
It is used mainly in industry (sanitary tubes, sheet metal, bars, ...)

The Cu-OF electronically deoxidized combines the qualities of the first two. Its purity is 99.95%, its conductibility is as good as the Cu-ETP and it is as easy to weld as the Cu-DHP.

It is suitable for a lot of scientific applications.