Here’s a detailed overview of the crushing flow chart at Holcim's Bombay Quarry, outlining the key stages and processes involved in transforming raw materials into usable aggregates:
1. Primary Crushing:
The process begins with the extraction of raw limestone from the quarry face using drilling and blasting techniques. The blasted material is transported to the primary crusher, typically a jaw crusher or gyratory crusher, which reduces large boulders into smaller, manageable pieces (approximately 150–200 mm in size). This stage ensures uniformity and prepares the material for further processing.
2. Secondary Crushing:
The output from the primary crusher is conveyed to secondary crushing units, often cone crushers or impact crushers. Here, the material undergoes additional size reduction to achieve intermediate sizes (around 20–50 mm). This step is critical for optimizing particle shape and minimizing fines. Screening may be integrated to separate oversized material for re-crushing.
3. Tertiary Crushing (if applicable):
For finer aggregates or specialized products, tertiary crushing may be employed using vertical shaft impactors (VSIs) or high-pressure grinding rolls (HPGRs). This stage further refines the material to meet specific gradation requirements (e.g., 5–20 mm). Dust suppression systems are utilized to control airborne particles.
4. Screening and Classification:
Crushed material is screened through vibrating screens to segregate it into various size fractions (e.g., coarse aggregates, chips, and sand). Oversized particles are recirculated back to secondary or tertiary crushers, ensuring efficient resource utilization. Advanced screening technologies enhance accuracy and throughput.
5. Washing and Scrubbing:
To remove impurities like clay or organic matter, aggregates may pass through log washers or sand screws. This step improves product quality, particularly for concrete applications where cleanliness is paramount. Water recycling systems are employed to minimize environmental impact.
6. Stockpiling and Dispatch:
Final products are stockpiled based on size and grade before being loaded onto trucks or conveyors for distribution. Automated weighing and tracking systems ensure accurate inventory management and timely delivery to customers.
Holcim's Bombay Quarry integrates modern automation and environmental controls to optimize efficiency while adhering to sustainability standards. Regular maintenance of equipment ensures consistent output quality and operational reliability throughout the crushing circuit.