Refinement is the process of separating the valuable metal from the unwanted material (gangue) and purifying it to a usable form. This stage is highly technical and varies greatly depending on the metal.
- Concentration: For many ores, the first step is to concentrate the valuable minerals. Common methods include:
- Flotation: Used for sulfides (e.g., copper, lead, zinc) where chemicals are added to a slurry to make the desired mineral particles hydrophobic, allowing them to attach to air bubbles and float to the surface, forming a concentrate.
- Gravity Separation: Utilizes differences in density to separate minerals (e.g., gold, tin).
- Magnetic Separation: Used for magnetic minerals like iron ore.
