Mineral Processing Plant

From rock to concentrate

A concentrator separates the small amount of valuable mineral from the large amount of waste rock. The animation shows a typical copper plant. The work happens in two big steps: comminution (making the rock small enough to free the mineral) and separation (floating the mineral away from the waste).

1. Primary crushing: trucks tip run-of-mine ore into a bin; a jaw or gyratory crusher breaks the big lumps.
2. Grinding: a conveyor feeds a SAG mill and then a ball mill. Steel balls and rock tumble together and grind the ore to fine sand.
3. Classification: hydrocyclones split the mill product. Coarse particles return to the ball mill (the circulating load); fine particles go on.
4. Flotation: reagents make the mineral water-repellent, air bubbles carry it to the surface and a froth of concentrate overflows. Banks of rougher, scavenger and cleaner cells improve recovery and grade.
5. Dewatering: the concentrate is thickened and filtered into a damp cake for shipping.
6. Tailings: the barren slurry goes to a storage facility (or to a paste plant for backfill), and the water is recycled.

Typical numbers (site dependent)

• Cyclone overflow to flotation is typically about 75–150 µm P80. At one large mine (Oyu Tolgoi) it is reported as about 140 µm at 33% solids.
• Copper concentrate is typically about 25–30% Cu, from ore that is often below 1% Cu, so most of the feed ends up as tailings.
• Grinding is usually the largest energy user, which is why liner design, mill speed and ball charge are watched closely.

Click any equipment in the animation, or a name above, to open a detailed animation of it.