Gravity Separation Methods

Gravity Separation

• Gravity separation involves various methods, including separation by jigs, spiral concentrators, and shaking tables.

Shaking Tables

• Wet shaking tables aid particle separation through a combination of factors: • Backwards and forwards motion (stroke) of the table • Tilt (longitudinal and lateral) • Wash water applied along the table's length • Riffles
• Operating variables for wet shaking tables include: • Tilt angle • Slope angle • Splitter positions • Wash water • Stroke length • Feed rate and density • Riffle height

Dry Shaking Tables

• Dry shaking tables or air tables are used for specialized dry gravity separation applications, such as fine quartz and zircon.
• Operating variables for dry shaking tables include: • Tilt angle • Splitter positions • Fan dampers (for air flow) • Stroke length • Feed rate

Design Principles of Magnetic Separators

• A magnetic field with a gradient in field strength is necessary to enhance particle movement in desired directions.
• Two key parameters to evaluate magnetic separators are energy consumption per tonne of material treated and machine mass per tonne of material.

Operational Requirements

• Commercial magnetic separators are continuous-process machines operating on a moving stream of particles passing through the magnetic field.
• Close control of particle speed through the field is essential, ruling out free fall as a means of feeding.
• Belts or drums are commonly used to transport feed through the field.

Magnetic Field Generation

• The magnetic field can be generated by: • Permanent magnets • Electromagnets with iron yoke • Solenoids • Superconducting magnets

Types of Commercial Magnetic Separators

• A broad grouping of commercial magnetic separators can be made into: • Low Intensity • High Intensity
• Both types can operate in either: • Wet • Dry

Magnetic Separation Process

• Magnetic force (Fm), gravitational force (Fg), and drag force (Fd) are involved in separating magnetic particles from non-magnetic particles.
• Particle size in feed is restricted by matrix type, e.g., matrix type XR 1.1 for particles.

This quiz covers the principles and techniques of gravity separation, including separation by jigs, spiral concentrators, and shaking tables. It also explores the operating variables that affect the separation process.