How are copper and nickel separated from Sudbury sulfide ores?

In the case of Sudbury sulfide ores, where the copper and nickel content is nearly equal, the separation process begins with crushing and grinding the ore. The minerals are then liberated from waste materials through selective flotation, where mechanical and pneumatic devices create air bubbles that carry sulfide particles to the surface.

To specifically separate the copper from the nickel, the resulting concentrate undergoes a second selective flotation process. This step floats the copper to produce a low-nickel copper concentrate, while the remaining material forms a separate nickel concentrate. Each of these concentrates is then processed in its own respective smelting line.1

Following this separation, the nickel concentrate may be smelted to produce matte, which is further treated through methods such as electrorefining or carbonyl refining to achieve high purity. During carbonyl refining, any remaining copper and precious metals are left in the residue to be treated separately.1