The updated PEA models the mining of the Miraflores breccia pipe deposit using a combination of open pit and underground mining methods. Seafield plans to develop a lower tonnage operation requiring a lower initial capital cost with a focus on processing the higher grade materials of the deposit in the first eleven years of the mine life. The lower tonnage option also carries less construction and start-up risk than the larger throughput alternatives.
The Updated PEA represents a low cost, achievable, standalone, near term production scenario for Seafield, occupying a small footprint of the current land position. The Company will review broader development of the Miraflores area going forward.
Open Pit Mining
The open pit is defined by two discrete mine phases with the first phase focusing on processing the higher grade materials of the deposit in the first 11 years of production. The open pit model contains measured and indicated resources. The higher grade component contains only materials above 0.6 g/t Au and is estimated to contain 3.01 Mt of mineralized rock with a grade of 1.48 g/t Au and 143,675 oz of contained Au in-situ before recovery and 200,838 oz of contained silver at a grade of 2.08 g/t. The open pit contribution to mill throughput averages approximately 266 t/d, but varies from no process plant feed to full contribution through the use of stockpiles in some years. After year 11, the lower grade stockpiled material will be fed into the mill. The lower grade materials are estimated to contain 1.70 Mt of mineralized rock with a grade of 0.90 g/t Au and 49,073 oz of contained Au in-situ before recovery.
The ultimate pit is 480 m from east to west, 400 m north to south with a maximum high-wall height of 350 m and volume of 7.3 Mm3. At a cut-off of 0.6 g/t Au, the overall strip ratio (waste: feed) of the pit is estimated at 5.8:1.
Within the Miraflores breccia pipe are a series of sub-vertical NNW and NW trending veins and highly fractured breccia zones that contain higher grade gold than the background breccia system. To date, Seafield has identified 21 higher grade structures within the deposit (See Company's press release dated April 2, 2013). The underground mining component of production will target the higher grade features below the open pit.
The mineralized rock in the updated PEA underground mine plan is estimated to contain 6.06 Mt (diluted) at an average gold grade of 2.32 g/t and average silver grade of 2.17 g/t. Before process recovery, the underground portion of the deposit is estimated to contain 451,216 ozs gold and 422,356 ozs of silver. The underground contribution to mill throughput is approximately 1,484 tpd during the time underground mine operations are in full production (first 11 years).
Considerable geotechnical data to date indicates that a sublevel longhole stoping method with 15 m sublevel spacing and backfill is the preferred mining method to recover the economic portion of the deposit. The Company is currently concluding its geotechnical studies for the next level of study, with all field and laboratory programs now completed and geotechnical modelling nearing completion.
An upper portal and initial production ramp, located to the west of and under the pit, will access the upper portion of the depositand is 437 meters long at a grade of -15%. A lower portal and ramp is situated on the east side of the deposit. This ramp will access the middle and lower portions of the deposit and is 393 meters long and runs at a -14% grade to the west and then spirals to the lower stope areas. All ramps and sublevel development are designed at 3 metres wide by 5 metres high.
Most Popular Stories
- Boehner Lashes Out Against Ted Cruz, Far Right
- TFA Recruiting DACA Recipients
- Hawaii Official Who Release Obama Certificate Only Victim of Plane Crash
- Holiday Shopping Off to a Slow Start This Season
- Ford Plans New Cars, Jobs in 2014
- Gold, Silver Slide on Prospects of Fed Exit
- 'Rape Insurance' Bill Passes in Michigan
- Ted Cruz Coloring Book Selling Briskly
- Kim Jong Un's Uncle Executed
- Scotch Whisky Sales Raise Distillers' Spirits