The missing piece to the Secondary Ventilation cost management puzzle….
Impact of fan energy on heat
100% of kW energy to operate ventilation fans is given off as electrical heat. As aiflow passes through the intake of each fan, in series within a ventilation circuit, the air temperature rises.
Typically, a twin-stage 180kW fan increases the air temperature by 1°C wet bulb. This additional heat underground then has to be compensated by the ventilation system.
A typical twin 110kW secondary fan costs between $250,000 to $450,000 per year to operate (based on 13c/kW to 23c/kw) whilst the secondary vent power cost can be up to 50% of a mine’s total power usage.
The high fan power cost of secondary ventilation has led to the implementation of remote fan starters and shift timers at many mines, along with the general rule to turn fans off in inactive areas.
The Lifter-Dukt™ section is designed to keep deflated ducting ‘lifted’ to its inflated depth, allowing mines to turn fans off and reduce power cost when mining areas are inactive.
When fans are turned off, the ducting deflates and sags by an extra 60% (as compared to its inflated depth). This creates issues in traffic areas of the mine, primarily where the fans are situated in declines where trucks are operating.