Why is gravity separation effective for concentrating cassiterite?

Gravity separation is highly effective for concentrating cassiterite because it is a notably heavy, dense mineral compared to the lighter waste materials, or gangue, with which it is typically associated.12

Because of this significant density difference, gravity-based methods can efficiently isolate the valuable tin ore from lighter particles. Common techniques used in this process include:1

• Jigging: A pulsed water stream causes the material bed to stratify by density, allowing the heavy cassiterite to settle into the lowest layer.1
• Shaking Tables: These devices use vibration and flowing water to stratify and separate finely grained ores, making them particularly well-suited for tin.1
• Sluice Boxes (Palongs): Often used in alluvial mining, these sloped channels use baffles to trap heavy minerals like cassiterite at the bottom while allowing lighter waste to wash away.3

These methods leverage physical properties to achieve concentration, providing a reliable way to process both alluvial deposits and certain hard-rock ores.13