Lac des Iles Property
The Lac des Iles mine consists of an open pit mine, an underground mine, a processing plant with a nominal capacity of approximately 15,000 tonnes per day, and the original mill (which has been idle since 2001) with a nominal capacity of approximately 2,400 tonnes per day. The primary deposits on the property are the Roby Zone, a disseminated magmatic nickel‑copper-PGM deposit and the Offset Zone.
On October 21, 2008 the Company announced that, due to depressed metal prices, it was temporarily placing its Lac des Iles Mine on a care and maintenance basis effective October 29, 2008. When the palladium prices began to recover in December 2009, the Company restarted operations, and on April 14, 2010 the Company announced that the Roby underground mine was back in production.
Mining Operations
The Company began mining the Roby Zone in 1993 using open pit mining methods. Ore and waste from the open pit is mined using conventional hydraulic 27 cubic meter and 23 cubic meter shovels, 190 tonne trucks, 187 millimeter blast hole drills and a fleet of conventional ancillary equipment. Mine waste is stockpiled outside of design pit limits.
Development of the underground mine commenced in the second quarter of 2004 in order to access the higher grade portion of the Roby Zone. The underground deposit lies below the ultimate pit bottom of the open pit and extends to a depth of approximately 660 meters below the surface where it is truncated by an offset fault. Commercial production from the underground mine commenced on April 1, 2006. For the three months ended March 31, 2009, no ore was extracted from the underground mine. During the same period last year, the underground ore had an average head grade of 5.66 grams per tonne of palladium.
The chosen mining method for the underground mine is sublevel retreat longitudinal longhole stoping with no fill. The mining block interval is 70 meters floor to floor including a 15 meter to 25 meter sill pillar below each haulage level. Stopes are 45 meters to 55 meters high by the width of the ore body. Total intake ventilation for the mine is designed to be 205 cubic meters per minute. There is one intake ventilation raise/secondary egress situated outside the ultimate open pit limits and air exhausts up the main ramp.
At the rate of production prior to being placed on temporary care and maintenance on October 29, 2008, open pit ore reserves would have been exhausted during the first half of 2009 and the current underground mining operation would have continued until late 2010 or early 2011. Management currently anticipates that high grade ore at the pit bottom will be accessed from the Roby underground mine.
It is envisaged that the Roby underground mine will support production at lower tonnage levels but higher grade than historical production. The Roby underground has identified reserves and resources for at least two more years. During this period, development work on the Offset Zone will continue with the objective of achieving a seamless changeover from the Roby underground to the Offset Zone.
