technical report on the nechalacho deposit, thor lake project ...

for closing unused areas and for checking areas prior to reopening unventilated areas will be
established to ensure that areas are suitably ventilated and that there are no noxious gases
present before work commences in a new area or an area which has been closed for some
time.
MINE AIR HEATING
In light of the sub-zero temperatures and the need to maintain the mine in an unfrozen state to
prevent freezing of water lines and or ground water the mine air will be heated using direct fired
mine air heaters located at the mine air intake. The mine air heaters will be approved units with
appropriate controls and automated shut down and alarms in the event of no flame or excessive
carbon monoxide.
Based upon the air flow of 200,000 cfm and heating of mine air to 35°F and the average annual
temperatures for Yellowknife the mine air heater will operate from late October to late April in
each year. The estimated propane consumption in this period is 1.5 million litres.
Mine Fan Horse Power
Scott Wilson RPA has estimated the mine resistance based using a friction factor “k” of 100
based on estimates from literature. The mine resistance in inches WG is then
The estimated headings were 800 ft of 12’ by 12’ intake raise and 6,000 ft of 16’ by 16’ drift
between the base of the raise and the exhaust generate a head loss of 2.76” WG at a flow rate
of 200,000 cfm.
The air horsepower is then estimated as flow times the head loss divided by 6,350. At 200,000
cfm and 2,76” WG head loss the air horse power is estimated to be 86 hp. Scott Wilson RPA
estimates that a 100 HP main fan will provide the desired 200,000 cfm of ventilation air flow.
Ventilation at 2,000 tpd Mining Rate
With the planned production rate increase to 2,000 tpd after year three there will be an increase
in the underground mine operating fleet and accordingly an increase in the mine ventilation
requirements. Scott Wilson RPA estimates that the required air flow will increase to 300,000
cfm as shown in Table 18-9.
Technical Report 43-101 – March 13, 2011 Page 18-24
Prepared by Avalon Rare Metals Inc.