Gualcamayo Gold Project

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This mine is 100% owned by Yamana Gold and is an open pit, heap leach operation encompassing three substantial zones of gold mineralization (QDD, AIM and QDD Lower West). In 2013 the QDD Lower West underground operation began production.

Surface rights in Argentina are not conferred with title to either a mining lease or a claim and must be negotiated with the landowner. In 2004, MASA purchased the surface rights to a contiguous land package totaling 26,218 hectare, which partially covers the Gualcamayo Project and wholly covers access to the area of interest from Highway 40, the main access route to the property.

Gold mineralization at Gualcamayo was discovered in 1980 by Mincorp Exploration S.A. (Mincorp), a subsidiary of Anglogold South America Ltd. Mincorp carried out an extensive exploration program of the Amelia Inés, Magdalena, and Belgrano zones of the property. Minas Argentinas S.A. (MASA), a wholly owned subsidiary of Viceroy Resource Corporation, acquired from Mincorp a 60% interest of the property in 1997, and the remaining interest in 2002. In 2003, Viceroy Exploration Ltd. (Viceroy) acquired MASA from its predecessor, Viceroy Resource Corporation. Yamana subsequently acquired Viceroy in early 2007.

The gold-bearing mineralized zones for the AIM deposit is primarily sulphide-bearing skarn, breccia and marble deposits containing minor copper, zinc and molybdenum with late stage gold-arsenic mineralization. The skarn contains minor chalcopyrite, sphalerite, galena, pyrrhotite, and pyrite that preceded the introduction of the gold-arsenic mineralization (AMEC, 2005). The gold mineralization extends beyond the skarn into the surrounding marbles.

The following summarizes the individual circuits included in the Gualcamayo process facility:

ROM ore is provided to the underground crusher from two sources: An ore pass fed from within the pit perimeter and an ore chute located outside the pit perimeter. A stationary grizzly with 650 mm openings to limit the feed size entering the ore pass and crushing circuit screen the ROM ore from the ore pass and ore chute. The ore pass and ore chute discharge material onto an underground conveyor system by Ross chain feeder and apron feeder respectively. Only one of these feed systems will be operated at a time. The conveyor discharges ore onto a vibrating grizzly with 150 mm spacing’s with the oversize material discharging into a jaw crusher set at a 150 mm closed side setting. The jaw crusher product and the vibrating grizzly undersize materials are conveyed to an intermediate ore stockpile using an overland conveyor. The ore from the intermediate stockpile is screened at 25 mm, resulting in a 100% -25 mm product, with the oversize material feeding a secondary cone crusher. The secondary cone crusher closed-side-setting is 40 mm, and is operated in open-circuit. The secondary crusher discharge is conveyed to the tertiary vibrating screen, also with 25 mm apertures, with the oversize sent to a tertiary crusher with a calculated closed-side setting of 24 mm. The tertiary crusher discharge combines with the secondary crusher discharge and is returned to the tertiary screen.

The secondary and tertiary screen underflows are conveyed to the leach pad, where it is stacked in 10-m lifts. Barren solution is distributed on the surface of the stacked ore using a drip system and percolates through the ore to dissolve the gold over a leach cycle of 30 days. The pregnant solution is pumped to a set of five carbón columns that contain activated carbon to recover the gold. The barren solution discharging from the columns is returned to the leach pad after adding fresh cyanide to a concentration of 500 mg/l.

The loaded carbon is advanced through an acid-wash circuit then to the gold desorption and stripping circuit where the gold is removed from the carbon with a high-pressure, high temperature caustic and cyanide solution. The stripped carbon is returned to a regeneration circuit for re-activation before returning to the carbon columns. The gold in the high-grade solution from desorption/stripping circuit is recovered by electrowinning. The electrowinning tailings solution is recycled to the desorption/stripping circuit. The electrowinning cell cathodes are cleaned and the sludge containing the gold is dewatered with a high-pressure filter and dried in an oven. The dried product is mixed with fluxes and smelted in a furnace to produce gold bullion.