ANS:B - Classifiers

Classifiers are used for the separation of coarse particles from a slurry of fine particles.

Explanation:

• Classifiers: These devices are specifically designed to separate particles based on size and density. In mineral processing and other industries, classifiers are used to separate coarse particles (oversize) from a slurry containing finer particles (undersize).
• Operation: Classifiers operate on the principle of settling velocity and particle size. Coarse particles settle faster than fine particles due to their larger size and higher density. The classifier uses this principle to separate the particles into different size fractions.
• Types of Classifiers:
  • Spiral Classifiers: Utilize the principle of settling velocity in a spiral pattern to separate particles based on size.
  • Hydrocyclones: Also used for particle separation based on size and density, where centrifugal forces are employed to separate particles.
  • Air Classifiers: Operate based on the principle of aerodynamic drag to separate particles of different sizes.
• Other Options:
  • Thickeners: Used for increasing the solids concentration of slurries by sedimentation of particles.
  • Hydrocyclones: Primarily used for separating particles based on density, size, and centrifugal force in a slurry.
  • Decanters: Generally used for liquid-solid separation, especially for clarifying liquids or separating fine particles from a liquid suspension.