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Cerro Corona

Cerro Corona consistently produces high-margin gold and copper from a single large open pit.

It is located in the highest part of the western cordillera of the Andes Mountains in northern Peru.

A well understood copper-gold porphyry ore body underpinning a robust LoM plan with optionality for expansion
Plant productivity increased to 830 tonnes per hour (tph) throughput in the second half of 2015 (813tph in 2014)
A feasibility study to assess the potential of increasing the Mineral Reserves will continue, and options to process the oxide stockpiles are being investigated
An exhaustive re-logging campaign has been conducted on almost 100% of the drill holes inside the Mineral Reserve pit to enhance resolution of the geological model
LoM extends to 2023 (eight years)
99.53% attributable to Gold Fields

Asset fundamentals

Asset fundamentals    
General location   The Cerro Corona deposit, centered at longitude 78° 37’ W and latitude 6° 45’ S, is at elevations ranging from approximately 3,600 to 4,000 metres above mean sea level. It is located 1.5km westnorthwest of the village of Hualgayoc, some 80km by road north of the departmental capital of Cajamarca, and approximately 600km north-northwest of the capital city of Lima.
Licence status and holdings   The mining concessions owned by Cerro Corona cover an area of 4,365 hectares while the surface rights cover 1,291 hectares. Cerro Corona is owned by GFLC, which holds 99.53% of the economic interest.
Operational infrastructure and mineral processing  

Cerro Corona Mine operates one open pit and one copper-gold plant.

The processing plant at Cerro Corona includes the typical equipment for a copper flotation plant, with a design capacity of 6.7Mtpa. The crushing plant comprises two jaw crushers in parallel. Crushed product is conveyed to a two-stage grinding circuit consisting of a semi-autogenous grinding (SAG) mill and a ball mill, in closed circuit with cyclones for classification. Cyclone overflow represents the final milled product and feeds the flotation plant. The rougher flotation produces a bulk concentrate, which is then reground and sent to cleaner flotation. The tails go to scavenger flotation, while the concentrate, with a grade of over 20% copper, goes to the next process.

The final concentrate is thickened and filtered before being stockpiled for road transport (380km) to the Salaverry port, for shipment to copper smelters in Korea, Japan and Germany. The thickened rougher flotation tails and the tails from the cleaner scavenger flotation are sent by gravity to the tailings storage facility.

Climate   There are no extreme climate conditions that may affect mining operations.
Deposit type   The Cerro Corona copper-gold deposit is typical of porphyry-style mineralisation comprising stock work quartz-pyrite-marcasite-chalcopyrite ± bornite ± hematite ± magnetite veining, hosted by intensely altered intrusive lithologies of diorite to dacitic composition.
LoM   It is estimated that the current Mineral Reserve will be depleted in 2023 (eight years).
Environmental, health and safety   Cerro Corona maintained its ISO14001 and OHSAS18001 certifications.

Cerro Corona was included in the Environmental Good Practice Registry of the National Environmental Agency as a consequence of good environmental performance in 2015. In Peru only three mining companies are part of this Registry.


Brief history of Cerro Corona

In 1979, exploration identified porphyry-style mineralisation in the Cerro Corona area. During the period from 1992 to 1993, sampling by the Gubbins Group identified gold mineralisation in the leached cap of the Cerro Corona deposit. Copper-gold porphyry mineralisation was discovered through the drilling of nine diamond core holes and completion of an exploration audit into the mineralised zone.

From 1994 to 1996, Cerro Corona then held by Barrick, drilled 140 reverse circulation drill holes totalling 9,476 metres and 118 diamond core holes totalling 35,254 metres. A draft feasibility study was completed by Kilborn. From 1997 to 1998, RGC Limited drilled six diamond core holes totalling 2,760 metres and a preliminary feasibility study was completed by Fluor.

In 2001, Minproc completed a number of feasibility studies, which ultimately indicated a Mineral Reserve of ~95Mt. In 2003, Gold Fields, through a subsidiary, signed a definitive agreement with Sociedad Minera Corona S.A. for the purchase of the Cerro Corona deposit and adjoining mining concessions.

The environmental impact assessment was approved on 2 December 2005 and the purchase transaction for the Cerro Corona Project was completed in January 2006. Mine construction commenced in May 2006. Building of the Las Gordas tailings dam and quarrying for the relevant construction material commenced in 2007. The mine started production in September 2008, when the process plant started to operate.

Gold Fields Corona (BVI) Limited, a wholly owned subsidiary of GFL, increased its economic interest in Gold Fields La Cima S.A. from the original 80% to 98.6% in 2012 and in 2013 to 99.53%.

Key developments at Cerro Corona

Cerro Corona remained the lowest All-in Cost per ounce (AIC/oz) producer in Gold Fields, producing high-margin gold and copper.
During 2015, the geological model was updated in terms of lithology, mineralisation, alteration and structure, using information from exploratory and infill drill holes, blast holes, in-pit mapping and an exhaustive re-logging campaign. Results have been incorporated into the enhanced resource model with improved density and hardness information, waste-ore contact definition and improved alteration-clay models.
A pre-feasibility study to assess the potential of expanding the LoM tonnage profile by configuring solutions to the current WSF and TSF constraints was undertaken in 2015. The study concluded that this was technically possible. Additional work on this study is scheduled in 2016.
The option to process the oxide stockpiles through the current sulphide plant is under review, both separately and in conjunction with sulphides. During 2014 and 2015, a number of laboratory and plant tests were performed with a mixture of material from the upper part of Number 1 and 2 oxide stockpiles and hypogene mineralisation from the pit. However, additional test work is required to confirm the best processing option and alternative treatment programmes are scheduled for 2016.
New geometallurgy models are now informing the short- to medium-term mining mix in the pit and the process blending to optimise concentrate delivery to the Salaverry Port.
The implementation of process improvement projects in the plant during 2015, is showing positive results in throughput and recoveries. During the second half of 2015, the plant operated at an average of 830tph, with a 72% gold recovery in the same period. Copper recovery also showed better performance despite an 11% reduction in the head grade.

Plan of the Cerro Corona mining area

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Geographic location
Geographic location

Related links
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