How does mineral processing concentrate copper minerals?

Mineral processing concentrates copper minerals by first crushing and grinding the ore to liberate the copper from waste material, known as gangue. The primary method for concentrating copper, particularly from sulfide ores, is selective flotation.1

In the flotation process, ground ore is mixed with water and chemical reagents to form a slurry. These reagents alter the surface properties of the minerals, making copper particles hydrophobic (water-repelling) so they attach to air bubbles introduced by mechanical or pneumatic agitation. As these bubbles rise, they carry the copper minerals to the surface to form a froth, which is collected as a copper concentrate. The remaining gangue, which is hydrophilic (water-attracting), stays in the cell and is discarded as tailings.12

While flotation is the most widely used method for fine-grained minerals, other techniques like gravity separation—which relies on density differences—can be used for certain ores, though they are less common for copper than for heavier minerals like tin or gold. The final copper concentrate is dewatered and filtered before being sent to a smelter.31