🎓 Lesson 2
D2
Core Principles and Theory
Blast design is the science of planning how to place and detonate explosives to break rock efficiently, safely, and with minimal environmental impact.
🎯 Learning Objectives
- ✓ Calculate optimal burden and spacing using the Kuz-Ram fragmentation model
- ✓ Analyze blast-induced ground vibration using the USBM scaled distance equation
- ✓ Apply powder factor to estimate total explosive consumption and associated CO₂e emissions
- ✓ Design a delay sequence to minimize peak particle velocity (PPV) while maintaining fragmentation efficiency
- ✓ Explain the relationship between blast design parameters and downstream supply chain carbon footprint (e.g., haulage fuel use, crusher energy demand)
📖 Why This Matters
Every ton of ore moved in mining starts with a blast—and every blast shapes the entire downstream supply chain’s carbon footprint. Poor fragmentation increases crushing energy by up to 30%, raises haul truck fuel consumption due to oversized boulders, and triggers re-drilling/re-blasting—adding emissions, cost, and delay. In carbon-constrained markets, blast design is no longer just about rock breakage—it’s the first lever for decarbonizing mine-to-mill logistics.
📘 Core Principles
Blast design rests on three interdependent pillars: (1) Energy coupling—the efficient transfer of explosive energy into rock fracture via confinement, stemming, and borehole pressure; (2) Fragmentation mechanics—governed by rock mass properties (RMR, Q-system), discontinuity spacing, and explosive energy density; and (3) Environmental propagation—how blast energy dissipates as ground vibration (PPV), airblast (dB), and flyrock, all constrained by regulatory limits. Modern practice treats blast design as a carbon-aware system: smaller burden/spacing improves fragmentation but increases drill meterage (and thus diesel emissions); lower powder factor reduces explosive CO₂e but risks poor breakage and higher downstream energy use. The optimal solution balances these trade-offs using life-cycle thinking.
📐 Kuz-Ram Fragmentation Model
The Kuz-Ram model predicts fragment size distribution (x₅₀) based on explosive energy, rock properties, and blast geometry. It is widely used to benchmark fragmentation quality and inform crusher feed sizing—directly impacting comminution energy, a major carbon hotspot in mineral processing.
💡 Worked Example
Problem: Given: ANFO density = 0.85 g/cm³, borehole diameter = 10.5 cm, burden = 3.2 m, spacing = 4.0 m, bench height = 12 m, rock factor (A) = 18 (competent granite), explosive strength factor (B) = 0.95 (ANFO relative to TNT), powder factor = 0.32 kg/m³.
1.
Step 1: Calculate rock factor-adjusted burden: B' = burden × A^(1/2) = 3.2 × √18 ≈ 3.2 × 4.24 = 13.57
2.
Step 2: Compute Kuz-Ram x₅₀: x₅₀ = 0.17 × (B')^0.8 × (PF)^−0.25 × B^0.25 = 0.17 × (13.57)^0.8 × (0.32)^−0.25 × (0.95)^0.25
3.
Step 3: Evaluate: (13.57)^0.8 ≈ 7.92; (0.32)^−0.25 ≈ 1.32; (0.95)^0.25 ≈ 0.99 → x₅₀ ≈ 0.17 × 7.92 × 1.32 × 0.99 ≈ 1.77 cm
Answer:
The predicted x₅₀ is 1.77 cm, which falls within the target range of 1.5–2.5 cm for primary crusher feed in hard rock applications.
🏗️ Real-World Application
At Newmont’s Boddington Mine (Western Australia), engineers revised blast designs across three pit benches to reduce average fragment size (x₅₀) from 22 cm to 16 cm—by decreasing burden from 4.0 m to 3.4 m and optimizing delay timing. This reduced secondary crushing energy by 18% and cut haul truck fuel use by 7% (due to fewer boulder encounters and improved loading efficiency), lowering Scope 1 & 2 emissions by ~12,500 tCO₂e/year—verified via site-level carbon footprinting aligned with GHG Protocol Scope 3 Category 1 (purchased goods & services) and Category 4 (upstream transportation).
🔧 Interactive Calculator
🔧 Open Supply Chain Carbon Footprinting Calculator📋 Case Connection
📋 Supply Chain Carbon Footprinting in Large-Scale Industrial Projects
Complex engineering requirements at scale
📋 Small-Scale Supply Chain Carbon Footprinting Implementation
Limited resources and tight budget
📋 Supply Chain Carbon Footprinting in Challenging Environments
Environmental and terrain challenges
📋 Cost Optimization in Supply Chain Carbon Footprinting
Maintaining quality while reducing costs