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Lac des Iles

 

Key Facts

Commodity Palladium, Nickel, Gold, Copper
Location

Ontario, Canada
Nearest Landmark: Thunder Bay
Distance:  85 Km NW from nearest Landmark
Latitude:    49° 10' (North)
Longitude: 89° 37' (West)

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Owners North American Palladium Ltd
Operator Lac des Iles Mines Ltd
Deposit Type Contact-type 
Production 146,624 oz payable palladium (2011)
Reserves & Resources 172 koz palladium (proven & probable, May 31, 2011)
Mining Type Underground
Mining Method Longitudinal and transverse long-hole open stoping & backfilling
Mining Equipment  
Processing Crushing, grinding, flotation
Employees 196
Processing equipment Gyratory crusher, SAG mill, ball mill, flotation circuit
Contact Information

Lac des Iles Mines Ltd
PO BOX 10547
Thunder Bay, ON
CAN P7B 6T9
Phone:+1 (807) 448-2000
Fax:+1 (807) 448-2001

 

Last updated: June 7, 2012

Overview

North American Palladium Ltd. Is one of the world's only two primary palladium producers. The Lac Des Iles (LDI) mine is located 85 kilometres northwest of Thunder Bay in northern Ontario. There is no nearby community and accommodations are provided at the mine camp.

The Lac des Iles deposit contains one of the largest bulk mineable palladium reserves in the world. The mine has been in operation since 1993; underground mining commenced in 2006 to access higher grade material.

The mine is an underground mining operation and open pit operations. The mining methods used are longitudinal and transverse long-hole open toping. There were 196 employees at the Lac des Iles mine. 

The ore crushing system includes a gyratory crusher, and secondary crushers. The crushed ore is processed in a standard flotation circuit. A palladium rich sulfide concentrate is produced and shipped off-site for final processing.

Payable palladium production for the year ended December 31, 2011 was 146,600 ounces.

In 2004 a final feasibility study confirmed the economic viability of the Roby zone located directly underneath the existing open pit, initiating the planning for the underground operations. Commercial production of the underground mine commenced in 2006. On August 16th, 2010 the company announced the results of preliminary economic assessment on the offset zone, which was discovered in 2001. The existing open pit and underground resources, particularly at the Offset Zone, represent potential to extend the current mine life.

The company is expanding the underground mine and intends to transform it into a long life asset that is also a low cost producer. The expansion is underway and it makes a transition from mining via ramp access to mining via shaft while utilizing a high volume bulk mining method. Commercial production from the shaft is targeted for the end of 2012.

Palladium represents approximately 59% of revenues generated from the operation. The remaining 41% are comprised of platinum, nickel, gold and copper.

Location

Lac des Iles is located 85 kilometers northwest of Thunder Bay, Ontario and Lake Superior. This is northwestern Ontario on the Canadian Shield, a vast rocky plateau, bordered to the south by Minnesota, to the west by Manitoba, and to the east by Thunder Bay. The Shield regions of northern Ontario are largely lakes, rocks and trees. Large parts of the region are monotonous, and the landscape rarely rises more than 100 meters.

Geology

The 1,465 ha property consists of 6 Crown Mining Leases comprising 3416.3 ha. Contiguous with these leases are 54 mineral claims consisting of 331 claim units covering 5,119.1 ha, for a total property area of 8,535.3 ha.

All of the known PGM reserves occur within a gabbro intrusion that is approximately 10 sq km in size and is part of the Lac des Iles intrusive complex. PGM and base metal mineralization in the Lac des Iles intrusion occurs in both primary and secondary situations within sulphide and silicate minerals. Mineralization appears to be dominantly stratabound along the contact between the East Gabbro and the mineralized Heterolithic Gabbro Breccia. Within the Heterolithic Gabbro Breccia, there is a high grade core typically constrained to an easily recognized ultramafic unit know as the Pyroxenite.

The Roby Zone Deposit is hosted within an Archean aged suite of mafic/ultramafic intrusives called the Lac des Iles Intrusive Complex. The Roby Zone Ore Body is dominated by varitextured gabbro containing pipes and pods of breccia. The breccia contains blocks up to (~60 m across) of varying lithology. Mineralization at Lac des Iles occurs as: (1) PGE-Ni-Cu rich breccias (breccia ore); (2) mineralized dikes or sills (North Roby Zone); and (3) within a 15 m to 25 m thick unit of high grade Pd mineralization located along the eastern portion of the Roby Zone in contact with the barren East Gabbro that forms the hangingwall of the deposit.

The Roby Zone is currently being exploited by means of underground mining methods. Mineralization to date at the Roby Zone has been outlined by surface trenching and diamond drilling over a 900 m long by 850 m wide area, and has been traced to a vertical depth of 1220 m.

The Offset High Grade zone (OHGZ) is believed to be the fault displaced continuation of the Roby Zone mineralization and is located below and approximately 250 meters to the west of the Roby Zone. 2011 drill results were positive and also indicated that the mineralized zone is still open in several directions.

The ongoing underground mine expansion is based on the Offset Zone.

Mining & Operation

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..

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.

The company is expanding the underground mine and intends to transform it into a long life asset that is also a low cost producer. The expansion is underway and it makes a transition from mining via ramp access to mining via shaft while utilizing a high volume bulk mining method. Commercial production from the shaft is targeted for the end of 2012.

The mine was placed on temporary care & maintenance in the period October 2008 - December 2009.

Processing

In 2001, a new mill facility was commissioned with a nominal design capacity of 15,000 tonnes per day. The processing operation utilizes a conventional flotation technology to produce a palladium-rich concentrate that also contains platinum, nickel, gold and copper.

Ore is first crushed in a gyratory crusher and conveyed to a coarse ore stockpile. With the commissioning of the secondary crusher in 2004, the coarse ore stream can be split so that a portion is crushed in the secondary crusher producing a fine material feed which is then combined with the coarse feed. This mixture of coarse and fine material feeds the SAG mill to increase mill throughput. In 2005, modifications were made to the secondary crusher, including the installation of a slide gate and better control feed distribution.

The ore is ground to a nominal P80 (the size of an opening through which 80% of the product will pass) of 74 microns in a conventional semi-autogenous mill/ball mill/pebble crusher (SABC) circuit. The ground ore then feeds a flotation circuit that is comprised of rougher/scavengers and four stages of cleaning. The flotation circuit in the old concentrator is currently connected to the new concentrator to provide additional cleaner flotation capacity. The final concentrate is thickened and dewatered using two pressure filters.

 

Environment & Community

The Lac des Iles Mine is a mature minesite that has followed the normal Ontario procedures of the Ministry of Northern Development and Mines (MNDM), Ministry of the Environment (MOE), and Ministry of Labour, through the local offices in Thunder Bay. All permits are in place to operate the open pit and underground operations. The minesite is in compliance with the Canada Fisheries Act, the Canada Water Act and the Canadian Environmental Protection Act.

Further development of the underground mine will not have a significant effect on the closure plan. The mine will be allowed to flood along with the pit. After removal of buildings, the only surface expression remaining will be the ventilation raise, which will be capped and fenced.

The closure plan amendment will also include the TMF expansion. A 140 ha south tailings cell is being erected for deposit of tailings to end of mine life. The current west TMF cell is filling up, and can be closed prior to end of mine life.

The mine operates seven days per week, 365 days per year. The hourly crews are divided into four crews, each working 12 hour shifts rotating one week on and one week off. The staff work four 12 hour shifts per week. The underground contractors are working 12 hour shifts, 7 days per week. Three crews rotate two weeks on and one off.

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