From the government of the NWT website history of mining in NWT. I believe it was the mill not the headframe that burned. See below.

http://www.iti.gov.nt.ca/mineralsoilgas/historyexploration.shtml

Discovery Mine

A.V. Giauque and sons first staked the Discovery property in 1944. Discovery Yellowknife Mines was formed in 1945, to explore the property. After extensive exploration in 1946, a shaft was sunk and in late 1949 a 90 tonne per day mill was installed. Discovery Mine operated between 1950 and 1969. Several auriferous quartz veins were mined up to the 1,200-metre level. A fire in 1969 prompted the mine closure.

Between March 1969 and 1980 there was no further work carried out. In December 1980 Newmont Exploration Ltd. optioned the property. They carried out ground geophysics, mapping and geochemical studies. During the summer of 1981 ground geophysical surveys (magnetic, VLFEM, HLEM) were carried out over a 60 line-km grid, and IP and resistivity surveys were performed over a more restricted area (covering the volcanic rocks). In 1987 Canamax Resources optioned the property and explored claims in the vicinity of Discovery Mine.

The property was allowed to lapse and was re-staked in 1992 by Gerry Hess. He formed New Discovery Mines Ltd. to develop the property. In 1994 the company drilled six holes totalling 915 metres. In 1995 GMD Resources Corporation entered into an agreement to earn in to the deposit. A decline was advanced approximately 100 metres in order to test the Ormsby Zone from underground. In 1996 approximately 100 diamond drill holes, totalling 22,769 m, tested the Ormsby and Discovery areas. A further 80,000 metres were drilled in 1997 and the data from these was used to calculate a new resource for the Ormsby Zone.