ENGINEERING AND PLANNING - Continued

Photo - Train underground hauling supplies and men

Underground Compressors

Seven underground compressors supply high-pressure air for all underground operations. Three were Ingersoll- Rand units each rated at 4144 cfm at 115 psi and four were Atlas Copco machines rated at 2285 cfm at 100 psi.

All were located in a room on the main 2600 level as were other underground shop facilities. Total capacity is 21,500 cfm at a maximum operating pressure of 125 psi.

Mine Ventilation

Life line of Granduc mine is the 10.3 mile tunnel connecting the mine with the Tide Lake concentrator. In an underground operation of the size of Granduc where mobile diesel- powered units were used so extensively, ventilation was one of the more important aspects of the entire operation. That it was successful was noted in the fact that no discomfort was felt at any time during the mine workings and that smoke and dust incidence was at a visible minimum.

Mine-air ventilation was drawn into the workings from an intake on the 3200 level on the Leduc side of the mountain. As was known this was the site for the original camp and was the main base for mine development prior to the breakthrough of the Tide tunnel. At that time two access tunnels were driven to the ore zones. The upper one at 3200 feet was chosen for the air intake.

Fresh air was drawn into the mine by two Joy 300 hp axial-flow fans; each delivers 225,000 c.f.m. It was blown along the ramps as fresh air was delivered to the working faces through flexible tubing supplied by A. B. C. Manufacturers of Saskatoon. The air passed through a series of ventilation raises to the 3100 level and after serving its purpose descended to the 2475 drainage level for exhaust.

The severity of the winter, which often say temperatures drop to well below zero required that the air be heated to avoid icing in underground areas. As a result an air-heating plant containing five diesel-fired package boilers was built. The plant had a capacity of 20,000,000 B. T. U .per hour and supplies hot glycol in closed circuit to heating coils upstream of the fans where heat transfer was made to the entering air.

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