The crushing of coking coal is a crucial step in the preparation of coal for use in coke production, which is essential for iron and steelmaking. Here’s an overview of the process:
1. Purpose of Crushing Coking Coal
– Reduces coal to a suitable size for carbonization in coke ovens.
– Ensures uniformity in particle size for better coking properties.
– Improves the efficiency of coal blending (mixing different types of coal).
2. Key Steps in Crushing Coking Coal
# (a) Primary Crushing
– Large lumps of raw coking coal are broken down using jaw crushers, rotary breakers, or impact crushers.
– Target size: ~50–100 mm.
# (b) Secondary Crushing
– Further reduction using hammer mills, roll crushers, or cone crushers.
– Target size: ~3–20 mm (optimal for coke oven charging).
# (c) Screening & Classification
– Screens separate crushed coal into different size fractions.
– Oversized particles are recirculated for further crushing.
# (d) Storage & Blending
– Crushed coal is stored in silos or stockpiles before 
nding with other coals to achieve desired coking properties.
3. Equipment Used
– Jaw Crushers – For initial coarse crushing.
– Roll Crushers – For intermediate crushing with minimal fines generation.
– Hammer Mills – Efficient for fine crushing but may produce more fines.
– Vibrating Screens – For size separation.
4. Factors Affecting Crushing Efficiency
– Coal Hardness & Moisture Content: Softer coals crush more easily; wet coal may clog equipment.
– Desired Coke Quality: Determines optimal particle size distribution.
– Coke Oven Requirements: Some ovens prefer a specific size range (e.g., 3–6 mm).
5. Importance of Proper Crushing
– Ensures better heat transfer during carbonization.
– Reduces coke oven wall pressure by preventing large particles from expanding unevenly.
– Enhances coke strength and reactivity.
6. Challenges in Crushing Coking Coal
– Generation of excessive fines can reduce coke yield and quality.
– Moisture can lead to handling issues (sticking, clogging).