The Bond Work Index (BWI) for limestone typically ranges between 10–15 kWh/ton (metric ton), depending on its hardness, purity, and geological formation.
Key Points:
1. Typical Range:
– Soft Limestone: ~10–12 kWh/ton
– Medium-Hard Limestone: ~12–15 kWh/ton
– Very Pure/Dense Limestone: May approach 16 kWh/ton (rare).
2. Testing Method:
The BWI is determined experimentally via the Bond Ball Mill Grindability Test (ASTM E408 or ISO 1456-1), which measures the energy required to reduce limestone from a theoretical infinite size to 80% passing 100 µm.
3. Factors Affecting BWI:
– CaCO₃ Content: Higher purity (≥95% CaCO₃) often correlates with lower work indices.
– Crystalline Structure: Fine-grained limestone grinds more easily than coarse-grained varieties.
– Moisture Content: Wet limestone may have slightly different grinding characteristics.
4. Practical Use:
The BWI is critical for designing grinding circuits (e.g., ball mills) in cement production, agriculture (lime), and mining.
For precise applications, conduct lab testing on your specific limestone sample, as regional variations can significantly impact results.
Would you like references to standard test procedures or data from specific limestone deposits?