The Magistral deposit is a calc-alkaline, copper-molybdenum, porphyry deposit with a well developed envelope of copper-(molybdenum) mineralized skarn (Ristorcelli et al., 2008).

There are three types of mineralization at the Project:
• Skarn: The skarn mineralization is of highest grade, forming a hundred-metre scale rim within the country rocks around the porphyries. Garnet (grossular at proximal and andradite at distal alterations), epidote, chlorite, hematite, magnetite, quartz and inosilicate minerals (pyroxene and amphibole) form the skarn gangue mineralogical assemblage. Centimetre-scale mineralized veinlets and massive patches of sulphide (chalcopyrite, pyrrhotite, pyrite, and minor molybdenite) crosscut the skarn gangue assemblage.

• Mixed zone: It consists of a metre-scale interlayering between the skarn and the porphyry style mineralization. It is possibly formed by the combination of exoskarn, endoskarn, and also intrusive fingers (porphyry), making a complex and variable sort of mineralization that combines mineralogical and grade characteristics of skarn and porphyry mineralization.

• Porphyry: The porphyry mineralization is of lowest grade and is formed by several quartz, chalcopyrite, and molybdenite veinlets (“D”, “B”, and “A”-type veinlets), which constitute a final stockwork framework that crosscuts the intrusive porphyry. The skarn mineralization seems to be preferentially elongated and anisotropic parallel to the strata bedding of country rocks (limestone), whereas the porphyry mineralization envelope is coincident with the limits of the San Ernesto and H porphyry intrusives, whose texture, grade, and mineralogy are apparently more isotropic than those of skarn mineralization.

The skarn mineralization seems to be preferentially elongated and anisotropic parallel to the strata bedding of country rocks (limestone), whereas the porphyry mineralization envelope is coincident with the limits of the San Ernesto and H porphyry intrusives, whose texture, grade, and mineralogy are apparently more isotropic than those of skarn mineralization.

The Project as currently designed will be an open pit mining operation. Open pit mining is proposed to be carried out by a contractor as a conventional truck and shovel operation.

It is contemplated that the mining contractor would undertake the following activities:
• Drilling performed by conventional hydraulic production drills.
• Blasting using ANFO (ammonium-nitrate fuel oil) and a down-hole delay initiation system.
• Loading and hauling operations performed with hydraulic excavators, and 35 t 8x4 haulage trucks.

The production equipment would be supported by bulldozers, graders, and water trucks. VMH would supervise the overall mining operation with its own employees including mining engineers, geologists, surveyors, and support staff.

Mineralized material will be fed directly into a primary crusher located adjacent to the open pit. Primary crushed material from the crusher will be transported to the processing facility using a system of conveyors.

Topsoil stripping will be required to gain access to mineral and waste rock below. The volume is estimated to be approximately 2.2 Mm 3 , which will be stored to the northeast of the pit. Waste rock will be sent to either the Valley Waste Dump (located west of the pit) or the North Waste Dump (located to the northeast of the pit).

As a portion of the material is expected to be potentially acid generating (PAG), this material will be stored in the North Waste Dump and is planned to be encapsulated within the non-acid generating (NAG) waste.

Run of mine (ROM) mineralization will be delivered to a primary gyratory crusher that is located adjacent to the mine. Crushed mineralization will be transported by a series of overland conveyor belts to a crushed mineralization stockpile that is located near the processing plant. Vibrating feeders will draw mineralization from the stockpile and transfer it to a conveyor belt that feeds the SAG mill. In the SAG mill the mineralization is mixed with water to form a slurry. Slurry from the SAG mill will discharge onto a vibrating screen. Oversize from the screen is returned to the SAG mill for further size reduction. The design includes sufficient space that a pebble crusher may be added to the circuit at a future date if it is determined that the pebbles reach a critical size that cannot be reduced by the SAG mill alone.

Undersize from the screen will be pumped to a series of high frequency vibrating screens that are designed to classify the mineralization to a particle size of 80% passing (P 80 ) 150 µm. Undersize from the screens flows to one of two ball mills while oversize from the screens is the final product from the comminution circuit.

The conceptual plant designed for Magistral will process 30,000 tpd using:
• Primary crusher
• Semi-autogenous grinding (SAG) mill
• Ball mill
• Bulk sulphide flotation circuit to recover copper and molybdenum
• Bulk concentrate regrind mill
• Copper – molybdenum separation flotation circuit
• Molybdenum concentrate regrind mill
• Molybdenum flotation circuit
• Dewatering
• Support systems

FLOTATION
Undersize from the high frequency screens will be pumped to a conditioning tank where reagents are added to the slurry. The bulk flotation circuit includes rougher and scavenger flotation circuits to recover bulk sulphide flotation concentrate that contains the copper and the molybdenum. The bulk rougher and scavenger tailings are the final tailings from the plant.

The bulk concentrate is reground in a ball mill that is operated in closed circuit with cyclones to produce a product size of P 80 45 µm. The ........