The Project is planned to be operated as an exclusively underground operation. The current mine plan includes only the sulfide material from the principal veins, which include veins CC, C1, A4, F1, G1, San Mateo, Roca Negra, Hiletas, Terneras, Chicago, and Escondida. The plan targets an annual maximum of 118,625 tonnes.
The past extraction methods used at the Velardeña mines are mechanized cut and fill stoping, mechanized resuing cut and fill stoping, and shrinkage stoping. These methods are suitable for the steeply dipping veins found at the Project.
For this PEA, the primary methods of extraction are expected to be cut-and-fill and resue mining. However, in practice, additional methods may be required due to adjust for dilution control due to the narrow vein widths at Velardeña (for example, shrinkage stoping).
Resue Cut and Fill Stoping
Mechanized resue cut and fill stoping is used when a vein system contains high grade material in a narrow width, less than one meter in width for the Velardeña vein packages. The following sequence outlines the stope life:
- Resue stoping begins by accessing the vein from a development drift with an attack ramp that enters the vein at a near perpendicular angle. The slope of the attack ramps ranges from -27% (initial) to +27% (final) to keep the attack development length to a minimum.
- The sublevel is driven by first taking a single 1.8 m round, 2.1 m wide by 2.75 m high, in the hanging wall ........