Copper is primarily extracted through mining, followed by concentration, smelting, and refining processes. Open-pit mining is the most common method.
Mining
The most common mining method is open-pit mining. This involves digging a series of stepped benches into the earth, creating a large, open pit.
- Drilling and Blasting: Boring machinery drills holes into the rock. Explosives are then inserted to break the rock apart, separating the copper ore from the surrounding material.
Concentration
After mining, the ore undergoes concentration to increase the copper content.
- Crushing and Grinding: The ore is crushed into smaller pieces and then ground into a fine powder.
- Froth Flotation: This process separates copper minerals from waste rock. The ore powder is mixed with water and chemicals in a large tank. Air is bubbled through the mixture, causing copper minerals to attach to the bubbles and float to the surface, forming a froth that is skimmed off.
Smelting
The concentrated ore is then smelted to produce a copper matte.
- Roasting: The concentrate is heated in a furnace to remove sulfur and other impurities.
- Smelting Furnace: The roasted ore is melted in a furnace, separating the copper matte (molten copper sulfide) from the slag (waste material).
Refining
The copper matte is refined to produce pure copper.
- Converting: The copper matte is further processed in a converter to remove iron and sulfur, producing blister copper (about 98% pure).
- Electrolytic Refining: Blister copper is refined using electrolysis. The blister copper is used as the anode in an electrolytic cell, and a thin sheet of pure copper is used as the cathode. When an electric current is passed through the cell, copper ions dissolve from the anode and deposit onto the cathode, resulting in a highly pure copper cathode (99.99% pure).
