ONTARIO – Detour Gold of Toronto has received a positive feasibility study for its Detour Lake gold project in the Abitibi Greenstone Belt. Start-up capital costs are estimated to be US$992 million. With average yearly gold output of 649,000 oz, Detour Lake will rival Osisko‘s Canadian Malartic mine (591,000 oz/yr Au and 754,000 oz/yr Ag) for the title of this country’s largest gold mine.
Proven and probable reserves at Detour Lake total 347.5 million tonnes grading 1.02 g/t Au or 11.4 million oz of contained gold. Global measured and indicated resources are 510.0 million tonnes grading 1.08 g/t Au at a cutoff grade of 0.5 g/t Au or 17.7 million oz of contained gold. An open pit will supply between 55,000 and 61,000 t/d to the mill over a 16-year life.
Conventional open pit mining is contemplated using a fleet of 36 haul trucks (300-t), two electric cable shovels (34 m3), three electric-hydraulic shovels (28 m3), six drills and various service equipment. The pit design includes 10-metre-high benches with a 35-metre-wide main haul road at a maximum grade of 10%.
The mill flowsheet includes conventional gravity, cyanidation and carbon-in-pulp (CIP) circuits. There will be two grinding lines each consisting of one semi-autogenous (SAG) mill (11 x 6 metres) and a ball mill (8 x 12 metres). About 30% to 40% of the gold will be recovered in the gravity circuit. After the CIP circuit, gold will be stripped from the carbon and processed through electrowinning cells prior to smelting.
The feasibility study puts operating costs at US$454 per oz of gold over the life of the mine. On a per-tonne-milled basis, the costs break down as US$6.82 for mining, US$5.21 for processing, US$1.12 for general and administration charges, US$0.03 for refining, plus a silver credit of US$0.13. The total costs will be US$13.05 per tonne milled.
The study indicates that the average annual pre-tax cash flow from production will be US$257 million. The net present value (NPV) at a 5% discount of the project is US$1.03 billion. The mine could pay for itself in 5.9 years.
These details and more can be found in the Detour Lake feasibility study to be posted soon at www.DetourGold.com.