Gravity Concentration Principles
Gravity concentration exploits differences in density between valuable minerals and gangue to achieve separation. It is one of the oldest mineral processing techniques and remains important for many applications, particularly for coarse, liberated particles.
Key Methods
Jigs:
- Use pulsating water to stratify particles by density
- Effective for coarse particles (>1mm)
- Common for coal, iron ore, and gold applications
- Simple, robust equipment
Spiral Concentrators:
- Use centrifugal force and gravity for separation
- Effective for fine particles (0.1-1mm)
- Common for coal, chromite and beach sand applications
- No power required — uses water flow
Shaking Tables:
- Use asymmetric motion to separate particles
- Excellent for fine particles (<0.5mm)
- High concentrate grade possible
- Common for gold, tungsten and tin
Gravity Concentration Methods
Centrifugal Concentrators
Knelson and Falcon Concentrators:
- Use high centrifugal force to retain heavy particles
- Excellent for fine gold recovery (-0.5mm)
- High recovery rates possible
- Batch or continuous operation
Falcon Concentrators:
- Continuous operation for high-volume applications
- Higher G-forces than Knelson units
- Suitable for precious metals and particle less than 0.2mm
Heavy Media Separation
Dense Medium Separation (DMS):
- Uses heavy suspension (ferrosilicon or magnetite) as medium
- Very precise separation possible
- Common for diamond recovery and coal
- Requires dense medium cyclone
WSHT provides gravity concentration equipment including jigs, spirals, tables and centrifugal concentrators for alluvial, placer and hard rock applications.
