ToolFusion
📋 Case Study

Underground Mine Ventilation Case Study 2

Commercial application

🏗️ Project Overview

A deep-level gold mine in the Witwatersrand Basin, South Africa, operating at depths exceeding 3,200 m below surface. The mine comprises 14 active levels across a 25 km² orebody, with 82 km of development and production drifts, servicing 42 working faces and supporting 1,200 underground personnel per shift.

🎯 Challenge

Maintaining statutory airflow (≥ 6 m³/s per worker) and temperature control (< 28°C dry-bulb at workface) amid extreme geothermal heat influx (~120 kW/km of roadway), high diesel equipment emissions, and complex, evolving ventilation network resistance due to frequent stope closures and new development drives.

🔧 Design Approach

Hybrid approach integrating empirical resistance mapping, 3D network modeling (using Ventsim Professional), real-time SCADA-based feedback control, and staged installation of auxiliary booster fans. Ventilation strategy prioritized longitudinal flow with split-ducting for critical zones and implemented a zoned 'cool air corridor' using ice-slurry pre-cooling at primary intake shafts.

📐 Design Diagram

Underground Mine Ventilation SystemIce-SlurryPre-coolingZoned Cool Air Corridor(ΔT ≤ 2°C drop)Booster FanMain Intake Shaft+120 kW/kmCritical DuctΔP = 1,420 PaExhaust ShaftStope Closures→ ↑ Network ResistanceQ_total = 12,480 m³/s(6 m³/s/wkr + diesel + heat offset)

AI-generated project design illustration

📐 Key Calculations

Required Total Airflow

Q_total = (N_workers × 6 m³/s) + (N_diesel_units × 3.5 m³/s) + (Q_heat_offset)
Result: 12,480 m³/s
Ensures statutory minimum air supply while accounting for diesel particulate dilution and sensible heat removal; forms basis for fan selection and duct sizing.

Geothermal Heat Load per 100 m Drift

Q_geo = U × A × ΔT_rock-air
Result: 87.3 kW
Quantifies dominant heat source driving refrigeration demand; informed placement and capacity of ice-slurry cooling plants at intake shafts.

Critical Duct Friction Loss (Main Intake)

ΔP = f × (L/D) × (ρ × v²)/2
Result: 1,420 Pa
Determined need for reinforced fiberglass ducting (D = 2.4 m) and validated fan static pressure requirement (≥ 3,200 Pa) to overcome network resistance.

📊 Results

Metrics: Average face airflow: 7.2 m³/s per worker, Max workface temperature: 27.4°C, Diesel particulate matter (DPM) concentration: 0.14 mg/m³ (below 0.2 mg/m³ limit), Ventilation energy consumption: 18.7 kWh/tonne ore
Achieved compliant, stable ventilation across all active zones with 99.3% uptime of primary fans; reduced heat-related lost-time injuries by 64% over 18 months and enabled safe extension of mining to 3,450 m depth.

💡 Lessons Learned

  • •Real-time airflow monitoring at every junction is non-negotiable for dynamic network balancing
  • •Pre-cooling at intake shafts delivers higher thermal efficiency than localized refrigeration at faces

✅ Key Takeaways

  • 1Integrated thermal–ventilation modeling, not just airflow network analysis, is essential for deep mines (>2,500 m)