How does mineral processing separate copper ore from gangue?

Mineral processing, or ore dressing, is the essential first step in separating valuable copper minerals from waste material, known as gangue. The process typically begins with crushing and grinding the mined material to liberate the copper minerals from the surrounding rock.12

The specific separation method depends on the ore type:

• Sulfide Ores: These are typically processed using selective flotation. The ground ore is mixed with water and reagents to create a slurry. When air is bubbled through the mixture, the reagents cause copper minerals to attach to the bubbles. As the bubbles rise, they carry the copper to the surface as a froth, which is collected as a concentrate, while the gangue remains in the cell as tailings.1
• Oxide Ores: These are frequently processed through leaching. In this method, the ore is crushed and ground to expose the mineral surfaces to a leaching agent, which dissolves the copper. The resulting solution is then treated through methods like electrowinning or solvent extraction to recover the metal.13