The Río Narcea Gold Belt is located in the western portion of the Cantabrian Zone in the northwestern part of the Hercynian-age Iberian Massif. The Cantabrian Zone and the nearby West Asturian-Leonese Zone consist of a stratigraphic section of Paleozoic sedimentary rocks that range in age from Middle Cambrian to Permian. The lower stratigraphic section of the Cantabrian Zone includes the Láncara Formation (Cambrian limestone), which is underlain by Cambrian feldspathic sandstone. The limestone has a total thickness of approximately 250 m and constitutes the principal host rock for gold and copper mineralization at El Valle-Boinás.

The 45 km long and four-kilometre-wide Río Narcea Gold Belt is characterized by the alignment of mineral occurrences, Paleozoic sediments, Tertiary Basins, fracture zones, and igneous intrusions. The most important igneous intrusions, from north to south, are the Ortosa-Godán, Carlés, Pando, La Brueva, Villaverde-Pontigo, and El Valle-Boinás intrusives.

Metamorphism in the Río Narcea Gold Belt is related only to intrusion of the igneous rocks, which produced contact metamorphism in the sedimentary rocks. They produce hornfels in the clastic units and skarn in the carbonate units.

Gold mineralization in the Río Narcea Gold Belt consists mainly of two types:

• Gold-bearing copper skarn: related to the interaction between late Hercynian intrusions, mesothermal solutions, and carbonate host rocks. This is the primary type of gold deposit that may be affected by later events (favourable host rocks for skarn include the Láncara Formation at El Valle-Boinás and the Rañeces Group Formation at Carlés).

• Jasperoid type: related to subvolcanic dykes and epithermal solutions which cause silicification with argillization and sericitization, plus epigenetic, hypogene oxidation. This type of mineralization may overprint, remobilize, and enrich gold mineralization within the skarn deposits, as happened at El Valle-Boinás. Also, this can form the breccia-style gold mineralization that produced higher grades at El Valle-Boinás. Limited to structural zones of varying width, they dip at high angles. They are typically the sites of leaching and enrichment that extend as much as 400 m below the surface.

EL VALLE-BOINÁS
The gold mineralization system has a strike length of two kilometres and a width of at least 0.5 km. The intrusive is elongated trending N35°E with a length of 500 m, and an average thickness of 300 m. A coppermineralization and that the resource model is reasonable and acceptable to support the updated 2014 Mineral Resource and Mineral Reserve estimates.

Gold mesothermal skarn was developed mainly along the contact between the igneous rock and the carbonate unit.

CARLÉS
The Carlés deposit is a gold and copper bearing skarn developed predominantly in the Devonian limestones of the lower portion of the Rañeces Formation along the north margin of the Carlés granodiorite. The Carlés intrusion is approximately circular in plan with a diameter of about 750 m.

Mineralization is continuous for over 1,000 m. It ranges in thickness from 1.5 m to over 25 m, dipping 50º to 90º away from the granitic intrusion. The skarn is known over a vertical continuity of 400 m and remains open at depth.

The current mining methods used at Boinás Mine are overhand drift and fill, and transverse longhole stoping. Due to decreasing thickness of the remaining Boinás skarns, RPA changed the design of the longhole mining from transverse to longitudinal where appropriate. Drift and fill mining will continue to be used in the oxide areas of the mine. Ore is hauled to surface via ramp and/or skipped via shaft, depending on location and ore type. Backfill is placed by truck and scoop, consisting of cemented rock fill or waste fill, as appropriate to the mining sequence and geotechnical demands.

Carlés Mine uses longitudinal longhole stoping methods. Ore is hauled to a surface stockpile via underground truck, and transferred to highway-rated surface trucks for transport to Boinás. Backfill is via waste fill, as stopes are separated by rib pillars.

The LOMP is currently a five year plan. The first three years are at full production with a reduction in production during the last two years. Carlés Mine will be placed on care and maintenance in early 2015, pending future increases in metal prices, new results from exploration, or determination of an economic mining method, such as conventional narrow vein mining.

CRUSHING
Ore extracted from EVBC is stockpiled and classified according to mineralogy, gold, copper, and/or deleterious element grades. When possible, a suitable ore blend is prepared to feed the mill with material containing 2 g/t Au to 5 g/t Au and < 1% Cu. A front end loader collects the ore from the various stockpiles and delivers it to the crusher feed bin equipped with a 600 mm aperture slotted grizzly screen. The crusher feed bin has an apron feeder that feeds the primary single toggle jaw crusher and any apron feeder spillage is collected on a conveyor belt below. The jaw crusher set to 153 mm. The spillage and the crushed ore which is less than 153 mm in size are transferred to the next conveyor belt equipped with load cell type belt weightometer and this belt discharges into the 100 ton mill feed bin. A level indicator and controller in the mill feed bin controls the apron feeder feed rate to the jaw crusher to maintain the set level in the bin.

The capacity of the jaw crusher (200 tph) is in excess of that for grinding. The mill feed bin can be allowed to overflow and can be diverted via a conveyor belt to the emergency storage stockpile that has a capacity of 1,000 tonnes. If the primary crushing circuit is not able to feed the grinding circuit directly due to maintenance, plant upsets, etc., then the mill feed can be supplied from the emergency storage stockpile.

The critical areas in crushing area have a wet system for dust control and the dust containing slurry is pumped to the mill discharge sump. A sprinkler irrigation system is also used for dust control in other open areas of the process plant.

PEBBLE CRUSHING
The semi-autogenous grinding (SAG) mill is fitted with pebble ports in the discharge end grate. The product leaving the SAG mill passes through a trommel screen with 12 mm apertures and the oversize is transferred via conveyor belt to the cone crusher. A moving belt magnet above this conveyor belt removes any tramp metal from the feed to the cone crusher and should any metal still be on the belt, a metal detector will open a by-pass chute ahead of the cone crusher to divert the feed to the cone crusher discharge return belt and damage to the cone crusher is prevented. The pebbles feed directly into the cone crusher which crushes the pebbles to < 12 mm. The crushed pebbles return to the SAG mill via a conveyor belt with a load cell type weightometer which weighs the total amount of pebbles that are recirculated. Should the pebble crushing circuit be off-line, the pebbles are diverted to an alternate conveyor belt that dumps the pebbles on the floor to be removed by a front end loader and stockpiled.

The installation of pebble crushing has resulted in a reduction in increased grinding capacity.

GRINDING
Dry crushed ore at P80 < 153 mm is fed to the SAG mill (5.5 m internal diameter by 2.3 m effective grinding length) by means of a conveyor belt equipped with a load cell type belt weightometer. The load signal controls the feed rate from the mill feed bin discharge conveyor onto the conveyor belt feeding the SAG mill. The pulp density in the mill is controlled by adding water to the SAG mill inlet. Oversize material is removed from the mill discharge pulp with the discharge end trommel screen. The oversize fraction is delivered to pebble crushing circuit, while the undersize fraction flows to the common pump box for both the SAG mill discharge and the ball mill discharge. The combined mill discharge is pumped to a cluster of seven 250 mm diameter Weir Cavex hydrocyclones for classification. The cyclone overflow reports to the flotation section and the cyclone underflow is split with part reporting to the gravity concentration section (approximately 100 tph) and the balance reporting to the ball mill feed. The ball mill has a 3.85 m internal diameter by 5.65 m effective grinding length. The cyclone overflow at 40% solids at has a size of P80 < 74 µm. If flotation is not necessary when processing low grade copper oxide ore then this flow can be diverted directly to cyanidation.

The processing plant consists of the following sequence of macro unit operations:
• Crushing and Screening
• Grinding and Cycloning
• Gravity Concentration
• Flotation Concentration
• Leaching/Adsorption via CIL process
• Gravity Concentrate Leaching (ILIX) (Intensive Lixiviation)
• Desorption and Elution
• Electrowinning
• Smelting
• Detoxification Plant for CIL Tailings Pulp
• Tailings Storage Facility (TSF).

Milling reduces the size of the ore to less than one mm and liberates metallic gold, copper and silver particles (in sizes between 100 µm to 500 µm) that is recovered by gravity concentration due to their density differences in comparison to the host rock. Two types of products are obtained from this circuit:
1. High grade gold in copper concentrate – treated in the ILIX plant.
2. Low grade gold in copper concentrate – final product for packaging.

The cyclone underflow that is split off to the ........