The document discusses various coal washing methods including jig washers, cyclone washers, and froth flotation processes. Each method has its own advantages in terms of separation efficiency and operational flexibility, but also presents challenges such as higher power consumption and costs. Additionally, it outlines coal storage requirements to ensure sufficient supply during peak firing rates.

1. Jig Washers
 A coal bed is maintained on a perforated plate
 Coal bed is subjected to action of upward and
downward current of water
 Clean coal being the lighter is concentrated at
the top while the dirt sinks and removed from the
bottom of the washer

2. Baum Jig
 This is the most common type of Jig Washers
 Baum Jig is U-shaped vessel divided into washing
and air compartments
 Compressed air is used to create the pulsating
movement of water

3. Advantages of Jig Washers
 Better separation efficiency for finer
sizes of coal (25-200mm)

4. Cyclone Washer
 The cyclone washer employs the same
principle as cyclone dust collector except that
the coal is fed in a STREAM OF WATER (or
dense medium) instead in air
 It is a settling chamber in which settling force
is replaced by centrifugal force
 The clean coal is obtained as an overflow from
the cyclone
 The underflow from the cyclone contains the
heavier material or impurities

5. Advantages
 Efficient for small sized coal
 High flexibility of operation with respect to
near gravity material, coal size and feed size
Disadvantages :
 Higher power consumption
 Higher maintenance cost
Cyclone Washer

6. Froth Floatation process
 Froth is made in a floatation cell by
bubbling air through water in presence
of frothing agents
 Frothing agents used are normally
cresol, pine oil or alcohols
 When dirty coal powder is added to cell,
the pure coal particles adhere to the
bubbles of the froth
 Dirt particles sink in the cell
 The clean coal is recovered by filtration

8. Froth Floatation process
Advantages:
 It can produce ultra pure coal
 It is suitable for fine coals
Disadvantages:
 High capital and running cost
 Coal must be grinded to less than 0.5 mm

9. 9
Coal Storage and Handling
 Solid fuels are stored in bunkers-normally
a quantity equivalent to 100 hours at peak
firing rate is the target storage capacity,
with a minimum amount of 20 tonnes.
 Coal is usually conveyed into storage from
the delivery vehicle by tipping or by
pneumatic conveyance along pipes.