ToolFusion
📋 Case Study

Underground Copper Mine Pillar Recovery Optimization

Post-extraction pillar instability threatening surface infrastructure

🏗️ Project Overview

Cerro Verde, Peru — Transition from room-and-pillar to sublevel caving

🎯 Challenge

Post-extraction pillar instability threatening surface infrastructure

🔧 Design Approach

Sequential pillar extraction with controlled blast sequencing, real-time convergence monitoring, and backfill slurry injection into voids

📐 Design Diagram

Surface Infrastructure Overburden Weak Pillar
(PSR=0.92) Extraction Ratio: 78% S1 S2 S3 S4 S5 Intact Pillar Weak Pillar Extracted Zone Monitoring / Injection Underground Copper Mine Pillar Recovery Optimization

AI-generated project design illustration

📐 Key Calculations

Pillar Strength Ratio (PSR)

Actual Pillar Strength / Required Strength
Result: 0.92
PSR < 1.0 indicates marginal stability

Extraction Ratio

Extracted Volume / Original Ore Volume
Result: 78%
Target range: 75–85% for stable transition

📊 Results

Safe pillar recovery at 82% extraction ratio; no surface subsidence >50 mm; 14% ore recovery uplift

💡 Lessons Learned

  • •Backfill modulus must exceed 1.5 GPa to limit stress redistribution
  • •Convergence thresholds must be set at 0.5 mm/day for early warning
  • •Blast sequencing must follow stress shadow propagation models

✅ Key Takeaways

  • 1Backfill modulus must exceed 1.5 GPa to limit stress redistribution
  • 2Convergence thresholds must be set at 0.5 mm/day for early warning
  • 3Blast sequencing must follow stress shadow propagation models