Copper: a metallic element

Copper is a metallic element originated in the depths of the Earth millions of years ago and which came to the surface pushed by the geological processes that shaped our planet. There it gave origin to several types of deposits.

In its most evident form it appears in veins with vey high copper content, even as native or natural copper. This form made possible its discovery by the primivite societies when they were barely beginning to know metals. These deposits are known as "vetiform deposits".

These deposits of native copper of high purity supplied mankind for a long time and, after thousands of years, they were finally exhausted.

Currently, most of the available copper appears sparsely distributed over large areas, mixed with mineralized materials and rock. These are the porphyric deposits, which could only be exploited when metallurgical skills to separate and recover the metal were developed.

There is a great number of compounds that contain copper, which are classified in two groups:

• sulfide
• oxide ores.

The percent of copper in these minerals is known as the "copper grade" and its value is variable. In some deposits this grade is of 1 to 1.8%, and often it is lower. In fact, most of the material extracted from mines has such a low grade that is considered waste.

Codelco sells copper to its clients in several formats. The most relevant product is the grade A cathode, 99.99% pure copper, shaped as a big metal plate, which is produced by electrowinning and electrorefining.

Another high purity copper format commercialized by Codelco is the fire refined ingot (RAF) obtained after succesive smelting processes.

The red metal is used in its pure form to fabricate a broad range of products, such as cables and pipes, but also as part of alloys in combination with other elements, such as zinc, tin, silver, lead, silica, berilium, aluminium...

The key to understand the intensive use of copper by mankind is in its basic properties: it is a metal that can be handled cold and hot, with great resistance to corrosion, of an attractive color, of high thermal and electric conductivity, ideal for communication transmission, it is not magnetic and it is completely recyclable.

These properties are transfered to the alloys using copper. The two more important ones, and known since antiquity, are bronze, a very hard material resulting from its combination with tin, and brass, copper with zinc, easy to manipulate and resistant to corrosion.