Q1: The study on washability of coal is done by using the __________ technique.

ANS:C - heavy media separation

The study on washability of coal is typically done using the heavy media separation technique. Here's why:

1. Washability Study:
   • The washability of coal refers to its ability to be separated into products of different qualities by washing.
   • This study is essential in coal preparation plants to determine the optimal conditions for separating coal from impurities (gangue) based on its physical and chemical properties.
2. Heavy Media Separation:
   • Heavy media separation (or dense media separation) is a technique used extensively in coal processing to separate coal from rock and other impurities based on their density differences.
   • In this process, a dense medium (often a suspension of finely ground magnetite or ferrosilicon) is used to create a fluid of specific density.
   • Coal particles with lower densities float on top of the dense medium, while heavier particles sink.
   • This method allows for precise control over the separation process based on the specific gravity of coal and impurities.
3. Other Techniques:
   • Tabling: This technique involves the use of a shaking table to separate minerals based on particle size and density. It is less commonly used for coal washability studies compared to heavy media separation.
   • Elutriation: This involves the use of fluid flow to separate particles based on size and density, and it is also less commonly used for coal washability studies.
   • None of these: Heavy media separation is specifically designed for efficient and effective separation of coal and is widely used for coal washability studies.