Refining of copper

Extraction of Copper from Its Ores

Copper is a valuable metal used in electrical wiring, plumbing, and many other applications. The extraction of copper from its ores involves multiple physical and chemical steps. The most commonly used ore for the extraction of copper is copper pyrite (CuFeS₂).

Major Steps in the Extraction of Copper

The process of extracting copper from copper pyrite involves the following main steps:

1. Crushing and Concentration: The ore is first crushed into small pieces and then concentrated using froth flotation. This process separates the copper minerals from the waste (gangue) materials.
2. Roasting: The concentrated copper ore is subjected to heating in a furnace where it reacts with oxygen. During this step, sulfur is removed as sulfur dioxide (SO₂), and iron is converted to iron oxide.
3. Smelting: The roasted ore is mixed with silica (SiO₂) and heated in a blast furnace. Silica reacts with iron oxide to form slag, which is removed. The resulting substance contains copper as a compound mixture known as matte, which primarily consists of copper(I) sulfide and iron sulfide.
4. Refining Matte to Produce Blister Copper: The matte is further heated in an air blast furnace where copper(I) sulfide reacts with oxygen to form copper metal and sulfur dioxide gas. This unrefined form of copper is known as blister copper, named after its blistered surface texture.
5. Purification by Electrolysis: The purification of blister copper is carried out through the process of electrolysis. In this process:
   • The anode is formed from the unrefined copper.
   • A thin sheet of pure copper acts as the cathode.
   • The electrolyte is an acidic solution of copper sulfate (CuSO₄).
   In the electrolysis process, pure copper accumulates on the cathode, and the impurities sink to the bottom as anode sludge or anode mud.

Final Product

After purification, the copper obtained is about 99.9% pure and is used in electrical conductors, pipes, and many industrial products.

The extraction of copper from its ore involves a combination of physical separation and chemical reactions. From crushing to electrolysis, each step ensures that copper is separated, purified, and made ready for industrial use.