How does flotation separation separate zinc minerals from waste rock?

Flotation separation is the primary method used to concentrate zinc minerals by isolating them from waste rock, known as gangue. The process relies on manipulating the surface properties of mineral particles to control their interaction with water and air bubbles.12

The procedure involves several key steps:

• Preparation: The ore is crushed and ground into a fine slurry with water.1
• Chemical Treatment: Selected chemical reagents are added to the slurry. These agents alter the surface of the zinc minerals, making them hydrophobic (water-repelling), while the gangue is treated to remain hydrophilic (water-attracting).12
• Agitation: The slurry is placed in flotation cells where it is agitated in the presence of air bubbles.1
• Separation: Because the zinc minerals are hydrophobic, they adhere to the air bubbles and float to the surface, forming an oily froth that is skimmed off. The hydrophilic waste rock remains wetted by the chemicals and sinks to the bottom of the cell.132

This technique allows for the efficient recovery of zinc from complex ores that would otherwise be difficult to process.2