Vale Coleman Mine (via BESTECH)

Underground mines face an inherent tension between worker safety and energy cost: continuous ventilation is non-negotiable for safe air quality, but running fans at full capacity around the clock regardless of actual occupancy drives enormous energy bills. As Vale's Coleman Mine deepened and expanded its working zones, the energy load from auxiliary ventilation fans grew proportionally. With mines operating 24/7, even marginal inefficiencies in fan scheduling compound into significant annual costs. Running ventilation at fixed, worst-case capacity — rather than responding to actual demand — represented a structural cost that Vale needed to address without compromising the safe environment required for underground personnel.

BESTECH designed and deployed an Integrated Architecture ventilation-on-demand (VOD) system that dynamically adjusts airflow based on real-time conditions rather than fixed schedules. The system uses Rockwell Automation CompactLogix PACs to collect and process data from underground air-flow sensors, then drives PowerFlex 700H and PowerFlex 7000 medium-voltage variable frequency drives (VFDs) to modulate fan speed in proportion to actual demand — accounting for worker locations, equipment activity, and air quality readings. The architecture integrates directly with Coleman Mine's existing underground infrastructure, enabling demand-responsive control across 16 auxiliary fans. By leveraging VFD technology, the system avoids the energy waste of throttled-but-running motors, translating sensor data into precise fan output in real time.

The VOD system delivered measurable improvements across energy, cost, and emissions from the point of deployment:

• $400,000 in annual energy cost savings across 16 connected auxiliary fans
• >30% reduction in ventilation energy consumption, exceeding the project's initial estimate
• ~3 million kWh saved per year, directly reducing grid draw from continuous fan operation
• 540 tonnes of CO₂ avoided annually, at a calculated rate of 1,577 kg CO₂ per kilowatt reduction

The results demonstrate that demand-responsive control at even partial fleet coverage — just 16 fans — can generate returns at scale. The system validated the VOD business case for broader rollout across additional fans and mine sections.

• VOD consistently outperforms projections: Coleman Mine exceeded its 30% savings target, suggesting conservative modeling is prudent when scoping ROI for similar implementations.
• Partial deployments still generate significant value: $400K annual savings from 16 fans underscores that mines don't need full-fleet rollout to achieve payback — phased deployment is viable.
• VFD selection is critical to outcomes: Medium-voltage drives (PowerFlex 7000) enable precise speed control at the power levels required for main auxiliary fans; specifying the right drive tier is a key engineering decision.
• Emissions reduction is a co-benefit worth quantifying: At 540 tonnes CO₂/year, VOD systems contribute meaningfully to corporate sustainability targets alongside their energy cost case.