Copper cathode is a form of copper that has a purity of 99.95%. In order to remove impurities from copper ore, it undergoes two processes, smelting and electrorefining. The resulting, nearly pure copper is an excellent conductor and is often used in electrical wiring.
When it is in the ground, copper does not exist in its pure form. Rather it is part of a compound. One of the most common types of copper ore is a mixture of copper, iron and sulfur. This ore is called chalcopyrite. After the ore is mined, it is heated in a furnace to 2,012° F (1,100° C). At this temperature, oxygen reacts with the iron in the ore, turning the ore into three substances, iron oxide, sulfur dioxide and copper sulfite.
After most of the iron is removed from the copper ore, the copper sulfite, which is also known as copper matte, is exposed to high levels of oxygen. The copper matte is still in a molten state, and the oxygen sent into the furnace is able to bond with the remaining sulfur, creating more sulfur dioxide and 99% pure copper.
At this point, the refined copper can be used for goods that do not require a high degree of conductivity, but the copper can be refined further into copper cathode through the electrorefining process. Many of the remaining impurities in the copper are traces of other minerals, including nickel, silver, and gold. These trace minerals are collected during electrorefining.
In electrorefining, the 99% pure copper is placed in a solution of sulfuric acid and copper sulfate. The sheets of impure copper are lined up next to materials that pure copper will deposit on. Electricity is sent into the tanks through the impure copper slabs, called anodes, and leaves through the pure copper that is formed, also called the copper cathode. Impurities in the copper either sink to the bottom of the tanks or rise to the surface as ions of pure copper travel through the solution to the cathodes.
As an excellent conductor of electricity and heat, copper cathode is often used to make copper wire. The pliable nature of copper makes it an excellent choice for electrical and audio wires, which must be thin and flexible. Aside from wire, copper cathode is also used to make copper cake, which ranges in thickness from thin foils to thick plates. Ingots of electrorefined copper may also be used to make alloys, such as bronze.