crushing of al in mining

The crushing of coal in mining is a crucial step in the coal preparation process, aimed at reducing the size of mined coal to facilitate handling, transportation, and further processing (e.g., washing or combustion). Below is an overview of coal crushing in mining:

1. Purpose of Coal Crushing

• Size Reduction: Coal extracted from mines often contains large chunks that need to be broken down into smaller, manageable sizes.
• Separation of Impurities: Crushing helps liberate impurities (e.g., rock, shale) embedded in coal for easier removal during washing.
• Improved Combustion Efficiency: Smaller coal particles burn more efficiently in power plants.
• Easier Transportation: Crushed coal flows better through conveyors and rail wagons.



2. Stages of Coal Crushing

Coal crushing typically occurs in multiple stages:
1. Primary Crushing
– Large lumps (~500–1500 mm) are reduced to ~100–300 mm using:
– Jaw Crushers
– Gyratory Crushers
– Rotary Breakers (also removes rock/shale)

2. Secondary Crushing
– Further reduces coal to ~50–100 mm using:
– Roll Crushers
– Impact Crushers (hammer mills)

3. Tertiary Crushing (if needed)
– Produces finer particles (~10–50 mm) for specialized uses (e.g., pulverized coal injection).

3. Common Coal Crushers

| Crusher Type | Application | Output Size |
|————-|————|————|
| Jaw Crusher | Primary crushing | 100–300 mm |
| Rotary Breaker | Primary + impurity removal | 50–200 mm |
| Roll Crusher | Secondary crushing | 10–50 mm |
| Hammer Mill | Fine crushing/pulverizing | <25 mm |

4. Key Considerations

• Moisture Content: Wet coal can clog crushers; pre-drying may be needed.
• Hardness/Abrasiveness: Affects crusher wear and choice of equipment.
• Sulfur & Ash Content: Influences downstream processing requirements.
• Environmental Controls: Dust suppression systems (water sprays, enclosures) are essential.

5. Post-Crushing Processing

Crushed coal may undergo:

• Screening (size classification)
• Washing (removal of impurities)
• Drying (for moisture control)
• Storage & Transport

6. Safety & Environmental Concerns

• Dust control measures (bag filters, wet suppression).
• Noise reduction (enclosures, vibration damping).
• Regular maintenance to prevent mechanical failures.

Would you like details on a specific type of crusher or optimization techniques?