Mount Polley Mine
- open pit copper/gold mine
- mill processes 20,000 tonnes per day
- commenced operations 1997
- current mine life to end 2025
- copper concentrate trucked to Port of Vancouver
- mine located 100 km northeast of Williams Lake
Mining in 2013 will focus on Springer Phase 3 and the adjacent Cariboo pit. The majority of ore feed will be sourced from Springer Phase 3, and the bulk of stripping activities will be in the Cariboo pit.
Throughput in 2012 was up 5% from the prior year, with over 8.1 million tonnes milled compared to 7.7 million tonnes in 2011. Increased throughput, improved recoveries and better grades resulted in increased copper and gold production of 27% and 22% respectively from the levels achieved in 2011. Mount Polley is expected to produce 38.5 million pounds copper and 43,000 ounces gold in 2013.
Mount Polley Annual Production
| Planned 2013 | 2012 | 2011 | 2010 | |
|---|---|---|---|---|
| Copper - lbs | 38,500,000 | 33,789,600 | 26,450,426 | 34,842,611 |
| Gold - oz | 43,000 | 52,236 | 42,514 | 46,771 |
| Silver - oz | 10,000 | 116,101 | 95,786 | 206,812 |
During the 2012 exploration program 45 drill holes totalling 24,715 metres were drilled in the Springer pit. The results were successful and resulted in a further increase in the resource. The results of the drilling beneath the Springer pit increased the reserve enabling a further expansion of the Springer open pit, adding two years to the mine life (to 2025).
As of January 1, 2013 reserves for Mount Polley are 98.4 million tonnes grading 0.294% copper and 0.297 g/t gold. The reserve has increased approximately 15% from the 2012 update. Milling this reserve and the low grade stockpiles would extend Mount Polley's mine life to the end of 2025. To achieve the updated mine life extension, additional stripping will be necessary. Two additional 793 haul trucks have been purchased to provide the haulage capacity required to accomplish the required stripping.
Initial test stoping from the Boundary zone is expected to begin in the second half of 2013. Underground drilling is currently underway targeting the Zuke zone, and the Halo zone, both of which are adjacent to the Boundary zone.
The grinding circuit consists of two parallel rod mill/ball mill circuits and a pebble mill circuit. Crusher product is first split between to two rod mills where it has water added to form slurries. The slurries are pumped to cyclones that classify the ore particles by size. The larger particles flow to feed the ball mills while the fine particles are discharged to the second stage of grinding: the pebble mill circuit. The ball mills are in "closed circuit", meaning that the discharge is pumped to the classifying units (cyclones) and the particles will not pass to the next grinding stage until they are fine enough to be classified as such. The second stage grinding circuit (the pebble mill circuit) also consists of mills, pumps and cyclones. Three pebble mills receive the coarse product from the cyclones, fed by pumps. The pebble mills are so named as they use pebbles (rocks obtained from the crusher) for grinding. Particles finer than 200 microns are then pumped as slurry to the flotation circuit.
The flotation circuit separates the valuable minerals from the waste minerals. The particle size reduction described above is imperative to separation as the mineral grains are very fine, with a mean diameter size of 50 microns. The valuable minerals, mostly in the form of sulphides, are separated from waste minerals (gangue minerals) by floating and being collected and upgraded or cleaned to produce a concentrate. Initial separation is done in a rougher/scavenger circuit, where the waste minerals are discarded as tailings (which flow by gravity to the tailings impoundment area). Rougher concentrate is further upgraded in a cleaner circuit to produce the final concentrate product. Cleaner tailings are recycled to the rougher/scavenger circuit.
The concentrate is dewatered in two stages. The thickener houses settling of particles and decanting of process water so that the settled particles forming a sludge has a reduced water content to roughly 35-40% water while pressure filtration further reduces water content to approximately 7.5%. The water removed is utilized as process water. The concentrate is stored in the load-out building and loaded on to 40-tonne trucks for shipping. Mount Polley's copper concentrate is then trucked to facilities at the Port of Vancouver, and shipped to overseas smelters. The principal market for Mount Polley concentrate is Asia. As of December 31, 2012 concentrate sales contracts were in place with three buyers for the purchase of Mount Polley copper concentrate. New concentrate sales arrangements are negotiated as required.
For additional information refer to the Company's Quarter Reports & Annual Information Form.
Forward Looking Information
As of January 1, 2013 reserves for Mount Polley are 98.4 million tonnes grading 0.294% copper and 0.297 g/t gold. The reserve has increased approximately 15% from the 2012 update. Milling this reserve and the low grade stockpiles would extend Mount Polley's mine life to the end of 2025. To achieve the updated mine life extension, additional stripping will be necessary. Two additional 793 haul trucks have been purchased to provide the haulage capacity required to accomplish the required stripping.
Initial test stoping from the Boundary zone is expected to begin in the second half of 2013. Underground drilling is currently underway targeting the Zuke zone, and the Halo zone, both of which are adjacent to the Boundary zone.
Mount Polley Air Photo: Current & Planned Pits (in gold)
Mount Polley Mill Infrastructure
In the Mount Polley mill, run-of-mine ore from the open pits is hauled to the crusher. The crusher has three stages of crushing involving five crushers, twenty conveyors and four sets of screens. The ore is dumped into the feed pocket of the primary gyratory crusher and the product is discharged to the grinding circuit at finer than approximately 20 mm particle diameter.The grinding circuit consists of two parallel rod mill/ball mill circuits and a pebble mill circuit. Crusher product is first split between to two rod mills where it has water added to form slurries. The slurries are pumped to cyclones that classify the ore particles by size. The larger particles flow to feed the ball mills while the fine particles are discharged to the second stage of grinding: the pebble mill circuit. The ball mills are in "closed circuit", meaning that the discharge is pumped to the classifying units (cyclones) and the particles will not pass to the next grinding stage until they are fine enough to be classified as such. The second stage grinding circuit (the pebble mill circuit) also consists of mills, pumps and cyclones. Three pebble mills receive the coarse product from the cyclones, fed by pumps. The pebble mills are so named as they use pebbles (rocks obtained from the crusher) for grinding. Particles finer than 200 microns are then pumped as slurry to the flotation circuit.
The flotation circuit separates the valuable minerals from the waste minerals. The particle size reduction described above is imperative to separation as the mineral grains are very fine, with a mean diameter size of 50 microns. The valuable minerals, mostly in the form of sulphides, are separated from waste minerals (gangue minerals) by floating and being collected and upgraded or cleaned to produce a concentrate. Initial separation is done in a rougher/scavenger circuit, where the waste minerals are discarded as tailings (which flow by gravity to the tailings impoundment area). Rougher concentrate is further upgraded in a cleaner circuit to produce the final concentrate product. Cleaner tailings are recycled to the rougher/scavenger circuit.
The concentrate is dewatered in two stages. The thickener houses settling of particles and decanting of process water so that the settled particles forming a sludge has a reduced water content to roughly 35-40% water while pressure filtration further reduces water content to approximately 7.5%. The water removed is utilized as process water. The concentrate is stored in the load-out building and loaded on to 40-tonne trucks for shipping. Mount Polley's copper concentrate is then trucked to facilities at the Port of Vancouver, and shipped to overseas smelters. The principal market for Mount Polley concentrate is Asia. As of December 31, 2012 concentrate sales contracts were in place with three buyers for the purchase of Mount Polley copper concentrate. New concentrate sales arrangements are negotiated as required.
For additional information refer to the Company's Quarter Reports & Annual Information Form.
Forward Looking Information