AMW Mining & Allied Services was engaged by M/s Eklavya Stone & Mines Pvt Ltd to optimise the blasting operation at the Bhadokara Stone Mines in Nawada District, Bihar. Using Kuz-Ram fragmentation modelling, pattern re-engineering, explosive selection and timing optimization, AMW delivered a measurable step-change in fragmentation quality and unit cost — without any increase in explosive consumption per tonne of stone produced.
Inconsistent fragmentation was driving up cost at every downstream stage
A closed-loop fragmentation engineering workflow
Every blast was audited over a full production cycle — hole geometry, charging, stemming, initiation and muckpile outcome. Rock mass assessment of the granite gneiss benches established UCS 100–160 MPa (ISRM "strong to very strong"), RQD 65–80 ("good"), in-situ density 2.60–2.75 t/m³, and a Kuz-Ram rock factor A ≈ 12. Joint orientation analysis identified strike-parallel open joints that were venting explosive energy and causing backbreak.
The Kuz-Ram model was used to predict mean fragment size (X₅₀) and the Rosin-Rammler distribution for candidate patterns before any hole was drilled. The model was calibrated against measured muckpile fragmentation, giving a reliable design tool for burden, spacing and charge per hole.
X₅₀ = A · K⁻⁰·⁸ · Q^(1/6) · (RWS/115)^(19/20)For 100 mm diameter holes on 9 m benches, the pattern was redesigned to burden B = 2.9 m (≈29 × d), spacing S = 3.2 m (S/B ≈ 1.10), subdrill 0.9 m (≈0.3 B) and stemming 2.6 m (≈26 × d) with drill cuttings. Staggered geometry and a stiffness ratio H/B ≈ 3.1 delivered uniform energy distribution across the bench.
B ≈ 25–40 d · S = 1.0–1.4 B · Subdrill ≈ 0.3 B · Stemming ≈ 20–30 dANFO (RWS 100) was retained for dry holes with site-mixed emulsion (RWS 110–120) specified for wet or water-bearing holes. Charge per hole was optimized against the Kuz-Ram prediction, and stemming quality was upgraded to eliminate fines-only stemming that was causing cratering and energy loss.
NONEL dual-delay initiation (25 ms inter-hole / 42 ms inter-row) was tuned iteratively. Muckpile fragmentation was measured after every blast using image-analysis techniques, feeding a closed-loop that refined the pattern until the target fragment size distribution was consistently achieved.
Measured outcomes after pattern stabilization
Secondary blasting dropped by 80% and breaker deployment was largely eliminated. Loading productivity improved by 20% with a consistent, crusher-friendly feed, and the mine achieved the same production with significantly lower explosive and drilling cost per tonne. Ground vibration at the nearest structures remained within DGMS Circular 7 of 1997 limits throughout.
Standards and regulations applied
AMW Mining delivers scientifically engineered blasting optimisation — fragmentation modelling, pattern design and timing — for stone mines and quarries across India and the GCC.
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