4 Basic unit operations of a coal washing plant
Comminution (Size reduction)
Breaking of raw coal.
$$ \text{Degree of liberation} = \frac{\text{Number of appearence of free grains}}{\text{Number of free grains} + \text{Number of locked particles}} \times 100 $$
Degree of liberation cutoff ($> 80%$).
Purpose of communtion:
- Liberate the particles
- Ease of handling
- Prepare the material of desired size of the end users.
Devices used for comminution
- Rotary Breaker (Slow speed)
- Roll Crushers (Slow speed)
- Hammer Mills (High speed)
- Ring Granulators (High speed)
$$ \text{Reduction size} = \frac{\text{Feed size}}{\text{Product size}} $$
Rotary Breakers
Size separation
Classify the particles into different sizes.
Benefication
- Coarse coal (> 0.5mm)
- Fine coal (< 0.5mm)