Cerro Corona Mine · The mining rights owned by Cerro Corona cover an area of 2,971 ha. The surface...

2

Cerro Corona MineTechnical Short Form Report31 December 2011

Gold Fields: Cerro Corona Gold Mine – Technical Short Form Report 2011 3

Salient points

¨ Mineral Resources at 7.7 Moz (gold and copper as Au-Eq).

¨ Mineral Reserves at 6.1 Moz (gold and copper as Au-Eq).

¨ A total of 161 koz of gold and 38.6 kt of copper were produced in C2011.

¨ ISO14001-OHSAS 18001 Integrated Management System Certification was achieved during 2011.

¨ The current Life of Mine extends to 2028 (17 years).

Cerro Corona, which is currently the most profitable mine in Gold Fields, is located in the highest part of the western Cordillera of the Andes Mountains in northern Peru and

produces gold and copper from a large open pit. The copper-gold concentrate is trucked to the port of Salaverry for export.

Geographic location

Cerro CoronaMining Concession

Cajamarca

Iquitos

Chiclayo

Trujillo

Lima

Cuzzo

PucallpaChimbote

Geographic location IFC

1. Overview Page 1

2. Key aspects Page 2

3. Operating statistics

4. Geological setting and mineralisation Page 4

5. Mining Page 7

6. Projects Page 7

7. Mineral processing Page 8

8. Sustainable development Page 8

9. Mineral Resources and Mineral Reserves Page 9

10. Regulatory codes Page 13

11. Competent Persons Page 13

12. Key technical staff Page 14

13. Brief history Page 17

Cer

ro C

oron

a ta

ilings

sto

rage

faci

lity

1. OverviewDuring 2011, Gold Fields Corona (BVI) Limited, a wholly owned subsidiary of Gold Fields Limited, increased its economic interest in Gold Fields La Cima S.A.A., or La Cima, from 80.7% to 98.5%. La Cima holds the Cerro Corona mine, which is located approximately 600 kilometres north-northwest of Lima and approximately 80 kilometres by road north of Cajamarca city.

The Cerro Corona mine is a large open-pit mine situated in the highest part of the Western Cordillera of the Andes Mountains in Northern Peru, approximately 1.5 kilometres west-northwest of the village of Hualgayoc in the Department of Cajamarca. Access to the Cerro Corona mine from Cajamarca is by means of two roads, one from Cajamarca to the Yanacocha mine (40 kilometres), and then from Yanacocha to the village of Hualgayoc (40 kilometres). The deposit is hosted by a subvertical, cylindrical-shaped diorite porphyry (600 – 700 metres in diameter), emplaced in mid-Cretaceous limestone, marls and siliciclastic rocks.

The mine is expected to produce approximately 2.0 million saleable ounces of gold and 423,000 saleable tonnes of copper in concentrate over a 17-year Life of Mine (LoM). At the declared commodity prices, the estimated copper and gold Mineral Reserves are equal to a total of 6.1 million gold equivalent ounces. The plant has a production capacity of 19,200 tonnes of ore per day, or about 6.6 million tonnes of ore per year.

This Technical Short Form Report provides brief information on the mining and operational performance for the twelve-month period ending December 2011 and also presents an updated Mineral Resource and Mineral Reserve statement as at 31 December 2011. Cerro Corona produces gold and copper by conventional open pit mining methods and beneficiation of sulphide ores by the extraction of a copper-gold flotation concentrate, which is trucked approximately 380 kilometres to the Peruvian port of Salaverry for shipment to smelters in Asia and Europe.

All Mineral Resource and Mineral Reserve figures reported are managed unless otherwise stated and Mineral Resources are inclusive of Mineral Reserves.

Cover image:

Cerro Corona pit at dawn

Note: For abbreviations refer to page 28 and for glossary of terms refer to page 29 – “Mineral Resources and Mineral Reserves Overview 2011”.

1


2. Key aspects

Independent audit Figures reported in this declaration are as reviewed by independent external consultants as at 31 December 2011 [SRK Consulting (Australasia) (Pty) Ltd for Mineral Resources and P&E Mining Consultants Inc. for Mineral Reserves]. Gold Fields has been informed that the audit identified no material shortcomings in any process by which the Agnew Mineral Resources and Mineral Reserves were evaluated

Prepared by Gold Fields Limited in compliance with the SAMREC Code (2007 edition)

Effective date 31 December 2011

Source of information This technical statement is a summary of the internally sourced document entitled December 2011 Cerro Corona Competent Persons Report

Personal inspection Personal inspection takes place by the Competent Persons as listed, who are full-time employees of Gold Fields Limited

General location The Cerro Corona deposit, centred at longitude 78° 37’ 8” W and latitude 6° 45’ 36” S, is located 1.5 km west-northwest of the village of Hualgayoc, some 80 km by road north of the departmental capital of Cajamarca, a city of more than 200,000 people and approximately 600 km north-northwest of Lima, capital of Peru

Climate No extreme climatic conditions are experienced that may affect mining operations

Licence status and holdings

The mining rights owned by Cerro Corona cover an area of 2,971 ha. The surface rights related to Cerro Corona is 1,264 ha. Cerro Corona is owned by Gold Fields La Cima S.A.A. (GFLC – 98.5% of the economic interest)

Operational infrastructure Cerro Corona Mine operates one open pit operation and one copper-gold plant at elevations ranging from approximately 3,600 to 4,000 m above mean sea level

Climate No extreme climatic conditions are experienced that may affect mining operations

Deposit type The Cerro Corona copper-gold deposit is typical of porphyry style mineralisation comprising stockwork quartz-pyrite-marcasite-chalcopyrite ± bornite ± hematite ± magnetite veining hosted by intensely altered intrusive lithologies of diorite to dacitic composition

Life of Mine (LoM) It is estimated that the current Mineral Reserve will be depleted in 2028

Environmental/Health & Safety

In August 2011 the Integrated Management System Certification ISO14001-OHSAS 18001 was achieved.

Reporting codes Gold Fields reports its Mineral Resources and Mineral Reserves in accordance with the South African Code for the Reporting of Exploration Results, Mineral Resources and Mineral Reserves (2007 SAMREC Code), and other relevant international codes such as SEC Industry Guide 7, JORC Code and NI 43-101. The Mineral Resources and Mineral Reserves are underpinned by an appropriate Mineral Resource Management process and protocol to ensure adequate corporate governance in respect of the intent of the Sarbanes-Oxley Act

Vie

w o

f Cer

ro C

oron

a op

en p

it m

ine

3

3. Operating statistics

Units Dec 2011 Dec 20101 June 2010 June 2009 June 2008

Open pit mining

Total mined kt 12,591 6,164 13,614 9,938 6,701

Waste mined kt 6,007 3,036 7,366 4,894 5,762

Sulphide tonnes mined kt 6,584 3,128 6,248 5,044 939

Strip ratio waste:ore 0.9 1.0 1.2 1.0 6.1

Gold: mined grade g/t 1.1 1.2 1.1 1.2 1.2

Copper: mined grade % 0.7 0.7 0.8 0.8 0.4

Processing

Sulphide tonnes milled kt 6,593 3,102 6,141 4,547 –

Au Head grade g/t 1.22 1.29 1.14 1.24 –

Cu Head grade % 0.74 0.79 0.85 0.78 –

Concentrate produced tonnes 190,007 92,390 194,201 118,848 –

Gold produced koz 161 80 139 105 –

Copper produced kt 39 20 41 24 –

Total gold equivalent produced eq koz 383 200 394 219 –

Total gold equivalent sold eq koz 383 201 390 218 –

Financial

Operating costUS$ million 157 77 135 86 –

US$/oz 411 388 343 394 –

Total cash cost US$/oz 437 395 348 369 –

Capital expenditure US$ million 69 31 86 117 –

Notional capital expenditure (NCE) US$/oz 592 545 561 926 –

General

Employees (TEC) number 1,106 997 1,128 875 543

Mineral Reserves Mt 110.0 86.2 89.2 89.3 94.1

Mineral Reserves Au Head Grade g/t 0.9 1.0 1.0 1.0 1.0

Mineral Reserves Cu Head Grade % 0.5 0.5 0.5 0.5 0.5

Mineral Reserves Au Moz 3.1 2.7 2.7 2.8 3.0

Mineral Reserves Cu Mlb 1,126 965 976 988 1,061

Mineral Reserves: Au Equivalent Moz 6.1 5.3 5.3 5.5 5.9

Expected Life of Mine years 17 14 15 15 161 Figures shown represent the six months to 31 December 2010. Rounding off of figures presented in this report may result in minor computational discrepancies. Where this occurs it is not deemed significant.

Vie

w o

f Cer

ro C

oron

a op

en p

it m

ine

Pan

oram

ic v

iew

of t

he C

erro

Cor

ona

oper

atio

n


The Cerro Corona copper-gold deposit is typical of porphyry style mineralisation comprising stockwork quartz-pyrite-marcasite-chalcopyrite ± bornite ± hematite ± magnetite veining hosted

by intensely altered intrusive lithologies of diorite to dacitic composition.

4

The Cerro Corona mine is located in northern Peru on the eastern slope of the western mountain range of the Andes. The copper-gold deposit is a typical porphyry-style of mineralisation situated within the Hualgayoc mining district in the northern part of the Cajamarca province, a metallogenic province hosting prolific epithermal, porphyry and polymetallic style mineralisation. The mining area is characterised by moderate to moderately steep mountainous terrain with elevations ranging from approximately 3,600 to 4,000 metres above mean sea level.

The Cerro Corona copper-gold porphyry is one of 14 known Tertiary-aged porphyry Cu Au Mo deposits and 19 epithermal Au Ag deposits located in the Cajamarca metallogenic province (CMP) of northern Peru. There are two well-mineralised districts within the CMP. These are the Yanacocha district in the south of the province, which is host to the largest producing gold mine in South America, and the Hualgayoc mining district in the north which is one of the oldest mining districts in Peru, best known for its past silver production and more recent base metal production.

This well-known district has been an important silver producing area since Inca times, with more than 50 Moz of silver and significant amounts of lead, zinc and copper produced from vein and manto-type deposits since the Spanish conquest in the 16th century. The Hualgayoc mining town was established in 1771.

The regional structure is characterised by large open folds of Cretaceous-aged sedimentary units, predominately limestones, with axial planes striking approximately 315° and steep southwest dips. Faulting is generally restricted to normal and oblique slip faults with offsets of a few metres to a few tens of metres.

Local geologyThe Cerro Corona copper-gold deposit is hosted by a 600 to 700 metre diameter subvertical cylindrical-shaped diorite porphyry emplaced in mid-Cretaceous limestone, marls and siliciclastic rocks. Within the porphyry,

4. Geological setting and mineralisation

Reg

iona

l geo

logy

and

met

allo

geny

of t

he C

ajam

arca

m

etal

loge

nic

prov

ince

Geo

logy

of t

he C

erro

Cor

ona

min

e ar

ea

the copper-gold mineralisation is primarily associated with zones of stockwork quartz veining conforming to classic porphyry-type vein definition. The Cerro Corona porphyry is unusual in that it carries a very high gold content in comparison to other copper-gold deposits.

There are at least two phases of diorite placement, only one of which is mineralised. The non-mineralised diorite is generally regarded as the last event, and is referred to as “barren core”. Most recent geological modelling strongly suggests that the Cerro Corona porphyry is probably comprised of four or five satellite stocks with the last two being barren. Early mineralisation was

ReferenceQuaternary

Miocene – VolcanicsOligo – Miocene intrusivesOligo – Miocene “Calipuy” volcanicsPaleocene sediments, continental

Upper cretaceous batholithCretaceous carbonates, sedimentsJurassic volcanicsTriassic – Jurassic carbonates

Paleozoic intrusivesPaleozoic metasediments

Precambrian metamorphicsMajor faultsChicama – YanacochaStructural corridorAlignment of porphyry depositsHigh sulfidation Au-AgDepositPorphyry Cu-AuDeposit

accompanied by moderate to strong potassic alteration, which has been commonly overprinted by late, semi-pervasive argillic alteration and locally, by structurally controlled phyllic alteration assemblages (quartz-sericite-pyrite).

The intrusive has been emplaced at the intersection of Andean parallel and Andean-normal (transandean) structures, which is a typical feature of the Cajamarca metallogenic province. A dominant north-east to south-west trending fault system running through the intrusive is referred to as the Mariela Fault trend and has an important relationship with the distribution of mineralisation. There are three distinct

25 km

N

9300 N

9200 N

Yanacocha

PERU

Hualgayoc

Cerro Corona

Mina Congas

Cajamarca

700 E 800E

LegendFaultPIT BoundaryProperty BoundaryQuarternary

Volcanic RocksVolcanic RhyoliticRhyolitic tuff

Intrusive RocksLas Gordas DioriteBellavista MonzodioritePorphyry granodioriticCerro Corona DioriteCore Barren NECore Barren SW

Sedimentary RocksChulec FormationMujarrun FormationPariatambo FormationYumagual lowerYumagual middleYumagual upper

Regional geology mapCerro Corona MineScale: 1/10,000 Date: December 2011Stratigraphy: J Jacay 2009Mapping & Interpretation by: A Uzategul OProjection: PSAD 56 Zone 17S

Cerro Corona PitT-di

Q

T-g-md

Las Tomastifault

Coymolache Fault

Magaly Fault

Carita Fault

Falla GaritaFalla Garita

Olga FaultMariela FaultPlanta Fault

Tizoc Fault

La Regalada F

ault

Polvorin Fault

Regala

da

II Fa

ult Olga Fau

lt

Manuela Fault

Rita Fault

El Zorro Fault

Consulado FaultLa Jalca Fault

Las Gordas Fault

Falla 1

Fallalas Tomas

Las Tomas I Fault

9250

000

9252

000

0 500 1 000 m

km-Ch

km-Yikm-Pa

T-g-md

T-riT-gd

T-ri

T-di T-di T-ri

T-ri

T-diT-ri

T-tri

km-Pa

km-Ym

km-Ym

Km-Ys

Km-Mu

T-g-md

T-g-md

T-g-md

Km-Mu

Km-Ch

Km-Pa

T-gd

Di

DIESWDIENE

Km-Pa

Km-Yi

Q

Q

Q

T-gd

km-Yi

T-gd T-ri

760000 762000 764000

km-Yi

Lucia FualtEl T

ingo

Fault

T-ri

T-tri

T-di

T-g-md

T-gd

DI

Diene

Diew

Km-ch

Km-Mu

Km-Pa

Km-Yi

Km-Ym

Km-Ys

Q

55

mineralised zones within the deposit. These are identified as the Annulus zone, the northern zone and the southern zone. Each of these is treated separately in geological and resource modelling.

In addition to the mineralised zones, the deposit is characterised by several domains conforming to the degree of oxidation and weathering. Supergene oxidation and leaching processes at Cerro Corona have led to the development of a weak to moderate copper enrichment blanket, allowing for the subdivision of the deposit, from the surface downward, into an oxide zone, a mixed oxide sulphide zone, a secondary enriched (supergene) sulphide zone and a primary (hypogene) sulphide zone.

Geological domainsOxidation, weathering, leaching and subsequent secondary enrichment has led to the formation of four mineral domains with distinctly different metallurgical behaviour, surrounded by barren intrusive and cretaceous sediments.

The topmost domain, the oxide domain, is characterised by the complete removal of copper mineralisation through the action of oxidation and leaching. Gold mineralisation within the oxide domain is characterised by some improvement in grade and is free milling due to the complete breakdown of primary sulphide minerals.

All of the ore beneath the oxide domain comprises parts of the sulphide zone, which is separated into three domains on the basis of the degree of oxidation and consequent change in sulphide mineralogical composition. The sulphide zone has three main domains, which from top to bottom are the mixed domain, the supergene domain and the hypogene domain. The hypogene domain is the primary sulphide zone. The supergene domain is an enriched copper blanket comprising chalcocite-covellite-chalcopyrite with grades in the range of 1% Cu.

Exploration and drillingAn in-fill diamond drill campaign was conducted during 2011 in order to improve the Resource model confidence at depth. In total 9,449 metres of core drilling were completed.

Reg

iona

l geo

logy

and

met

allo

geny

of t

he C

ajam

arca

m

etal

loge

nic

prov

ince

Geo

logy

of t

he C

erro

Cor

ona

min

e ar

ea

Geo

logy

of t

he C

erro

Cor

ona

Intr

usiv

e A

ltera

tion

map

at 3

820

benc

h le

vel

Pla

n vi

ew s

how

ing

the

Geo

logi

cal D

omai

ns a

t Ben

ch 3

800


AlterationWeak potassic

Phyllic (silicification)

Moderate argillic-phyllic

Moderate argillic

Strong argillic

Moderate propylitic

Geological Domains

Oxide

Mixed

Supergene

Hypogene

Barren Diorite

Cretaceous Sediments

Plan view RL 3800


Volcanic RocksVolcanic RhyoliticRhyolitic tuff

Intrusive RocksCerro Corona DioriteCore Barren NECore Barren SW

Sedimentary RocksChulec FormationPariatambo FormationYumagual lowerYumagual middleYumagual upper

Alteration map – Bench 3820Cerro Corona MineScale: 1/2,000 Date: December 2011Mapping & Interpretation by: A Uzategul – E AyalaProjection: PSAD 56 Zone 17S

Local geology mapCerro Corona MineScale: 1/2,500 Date: December 2011Stratigraphy: J Jacay 2009Mapping & Interpretation by: A Uzategul OProjection: PSAD 56 Zone 17S

0 50 100 150 200

T-ri

T-tri

DIDiene

Diew

Km-ch

Km-Pa

Km-Yi

Km-Ym

Km-Ys

Q

9252

000

9252

500

9252

000

92

5250

0

0 100 200 m

DIENE

DIESW

Km-Pa

Km-Ch

762500 763000 763500 764000

763000 763500

Km-Yi

N

Km-Ym

Km-Ys

Km-Yi

Q

Q

Di

Manuela Fault

La Gringa Fault

El Zorro Fault

Olga Gault

Diana Fault

Nancy Fault

Rosa Fault

Mariella Fault Julia Fault

Violeta Fault

Ela Fa

ult

Olga Fault

Regala

da II

Fault

La Reg

alada F

ault

Magaly Fault

La Jalca Fault

Polvorin Fault

Olga Fault

Mariela Fault

Carmen Fault

+9252600

+9252500

+9252400

+925300

+

+925

+925200

+9251900

+9251800

Elev (Z)

+763

000

+763

100

+763

200

+763

300

+763

+763

500

+763

600

+763

700

East

(X)

0 100 200 m


Dia

mon

d D

rill a

nd R

C H

oles

in th

e C

erro

Cor

ona

Min

eW

est-

Eas

t sec

tion

thro

ugh

the

Cer

ro C

oron

a in

trus

ion

(Nor

thin

g 92

5210

0)

show

ing

inte

rpre

ted

geol

ogic

al d

omai

ns

Plunge 00, Azimuth 000

0 50 100 150

Legend holesAbsent

DDH – 2011 Drill Holes

Diamond Drill Holes

Reverse Circulation Drill

West East Projection

Section 9252202-N (View to North)

Scale 1:4500.0 Date: 05/02/12 Time: 08:15

+763

000

+763

100

+763

200

+763

300

+763

400

+763

500

+763

600

+763

700

East

(Y)

Elev (Z)

+3950

+3900

+3850

+3800

+3750

+3700

+3650

+3600

+3550

+3500

762300 E 763200 E 763600 E

762300 E 763200 E 763600 E

4000 Elev

3800 Elev

3600 Elev

3400 Elev

4000 Elev

3800 Elev

3600 Elev

3400 Elev

Geological domains

Oxide

Mixed

Supergene

Hypogene

Barren Diorite

Cretaceous Sediments

View N9'252,1000

Looking North

7

Min

ing

in p

rogr

ess

in th

e C

erro

Cor

ona

pit

5. Mining

The Cerro Corona deposit is mined by conventional surface mining methods. The final surface mine area is expected to cover some 900 by 1,000 metres. The mining operation is extending from the crest of the original Cerro Corona hill, which peaked at 3,964 mRL, to a final depth at around 3,510 mRL.

Cerro Corona is mined via open pit methodology by conventional drill and blast with a truck and front-end loader fleet. Load and haul is by 90 tonne dump trucks and 11.3m3-front end loaders. Mining benches are all 10m high.

At this stage it is assumed that all of the material requires drilling and blasting (with varying powder factors) utilising 200 millimetre holes.

Mine planning and schedulingCerro Corona’s LoM plan is based on detailed geological and resource models. The LoM plan is established from detailed short-term and long-term mining design and schedules using specialised Xpac© software and a resource estimation model termed the localised multivariate uniform conditioning model (LMUC).

The planning cycle commences with the ratification of key input parameters prior to producing a compliant Mineral Resource statement. The planning process starts after the construction of the resource model and incorporates the following considerations:

¨ Corporate decision on macro-economic parameters; ¨ Development of a broad planning strategy, identifying key

mining and processing constraints; ¨ Development of comprehensive operating costs for

mining, processing, administration and selling; ¨ Modelling of the strategic, geological, geotechnical,

metallurgical, environmental and economic parameters; for application of the Lerchs Grossman algorithm. Subsequently, development of a broad economic sequence and an optimum ultimate economic pit shell;

¨ Development of a pit design and push-backs applying mine design parameters; and

¨ The reserve model contained within the pit design is scheduled with consideration of impacting factors such as the following:

– Economic valuation of each measured or indicated block considered for processing;

– Optimum practical economic sequence as generally defined by the push-backs;

– Structural material required for earth structures; and – Constraints related to the deposition of tailings and

overburden material.

Open pit optimisations are built using Whittle 4X© multi-element standard mine design software on the Localised Multivariate Uniform Conditioning (LMUC) resource model. Multiple-case scenarios are run using varying gold and copper prices, processing costs, mill recovery values and inclusion/exclusion of Inferred material to ensure that the optimal pit is selected. However, no Inferred Mineral Resource material is included in the Mineral Reserves. The work undertaken includes:

¨ Geotechnical review and pit wall angle recommendation; ¨ Cost review; ¨ Pit optimisation; and ¨ Sensitivity analysis.

Cerro Corona Mine operates one open pit operation and one copper-gold plant at elevations ranging from approximately 3,600 to 4,000 m above mean sea level.

6. Projects

Cerro Corona has initiated a scoping study for processing ~7.5 million tonnes of oxide ore by the heap leaching technique. These oxide ores, much of which are already stored in surface stockpiles, are estimated to contain approximately 300,000 ounces of gold that could potentially be processed within five years.

A scoping study to evaluate a full mine and sulphide process plant expansion for Cerro Corona is currently in progress. This project is expected to be completed by June 2012.

The current sulphide plant is being optimised with several small to medium projects, some to increase production and others to increase recoveries. These projects are scheduled for completion by Q1 2013.

An exploration programme to test the mineralisation at depth (>1,000m) at Cerro Corona is planned for C2012.

Dia

mon

d D

rill a

nd R

C H

oles

in th

e C

erro

Cor

ona

Min

eW

est-

Eas

t sec

tion

thro

ugh

the

Cer

ro C

oron

a in

trus

ion

(Nor

thin

g 92

5210

0)

show

ing

inte

rpre

ted

geol

ogic

al d

omai

ns


8. Sustainable development

The remote location of the operation means that local communities are particularly reliant on Gold Fields for socio-economic development, as well as basic infrastructure, such as roads and telecommunications. The well-being of local communities is an imperative aspect in Gold Fields La Cima S.A.A policies. Consequently, it has been a part of the business model to implement social development programmes in order to demonstrate corporate commitment from the initial exploration stage in Cerro Corona. Our target is to join forces and be a strategic partner with direct and indirect influence in regional development and sustainability projects.

In August 2011 the Integrated Management System Certification ISO14001-OHSAS 18001 was achieved. No fatalities were recorded in C2011 and 11.9 million man work hours without any

lost time injuries (LTI) were accumulated since the previous injury.

Sch

ool b

uilt

by G

old

Fiel

ds in

Hua

lgay

oc

7. Mineral processing

Vie

w o

f the

sur

ge ta

nk in

the

proc

essi

ng p

lant

The various ore types from the mine are stockpiled on the run-of-mine pad. They are fed in appropriate blends by front-end loader to the crushing plant. This comprises two mineral sizers in parallel, one of which is a standby unit. Mineral sizers facilitate crushing of soft, wet ore with clay components. The crusher feed design also makes provision for direct tipping of ore from the mine if necessary.

Crushed product is conveyed to a two-stage grinding circuit consisting of a SAG mill and a ball mill in closed circuit with cyclones for classification. Cyclone overflow represents the final milled product which feeds the flotation plant consisting of two sections. The rougher-scavenger flotation produces a bulk concentrate, which is then reground and upgraded to smelter copper grade in the four stage cleaner flotation section.

The final concentrate is thickened and filtered before being stockpiled for final shipment to the smelters. The thickened rougher-scavenger flotation tails and the tails from the cleaner flotation are pumped to the tailings storage facility.

Metal recoveries have been modelled as grade-dependent non-linear relationships, for both copper and gold. Some other factors such as clay content, high Fe/Cu grade ratio and rock acidity, appear to be influencing the metallurgical behaviour.

During calendar year 2011, initiatives to optimise the metallurgical recoveries were put in place:

¨ Detailed mineralogical description: This has been developed in detail for the mining polygons planned as plant feed, allowing metallurgists to define the appropriate reagent recipe for the different ore types.

¨ Geo-Metallurgical Units (UGM): Six Geo-Met Units were defined for the Cerro Corona ore body. This work was performed jointly with an external consultant.

¨ Work Index Comparative: Polygons from different areas of the pit were studied by an external laboratory to determine work index variation. This information will be used by the Geo-Met team to improve plant performance by adding a more reliable hardness parameter to the blending process.

¨ Blasthole – Surface Sample Comparative: Comparative test work was performed to demonstrate better representivity of blast-hole samples.

¨ P80 Analysis: P80 (screen opening that allows passing 80% of the sample) test work was made to different polygons. This information will also help the Geo-Met team to design better blending parameters or the production team to adjust operation parameters to improve gold and copper recoveries.

¨ Variability test works: To determine the heterogeneity of the different polygons.

The processing plant at Cerro Corona includes the typical equipment for a copper flotation plant. Design capacity considered treating 775 (current 800) tonne/hour at 91.3% (current 95%)

availability to reach an annual treated tonnage of 6.6 million ore tonnes.

9

Sch

ool b

uilt

by G

old

Fiel

ds in

Hua

lgay

oc

9. Mineral Resources and Mineral Reserves

The Mineral Resources and Mineral Reserves are reported from the new localised multivariate uniform conditioning (LMUC) model at a Net Smelter Return (NSR) cut-off of US$18.01/t and constrained within an optimised whittle pit shell, based on the same economic parameters as the NSR calculation. The Mineral Resources are constrained by the capacity of the waste storage facility of 150 million tonnes. The Mineral Reserves are constrained by the total capacity of the upgraded tailing storage facility of 130 million tonnes.

The estimation reported in the December 2010 Competent Persons Report was based on a LoM case with the Tailings Storage Facility (TSF) crest at 3,800 mRL and 100 million tonnes treated. Since then feasibility work has progressed on the technical and financial viability of a TSF crest at 3,815 mRL and 130 million tonnes treated in the LoM. These investigations have proved positive and consequently the case with the TSF at the peak elevation of 3,815 mRL and 130 million tonnes of ore (110 million tonnes post Dec 2011) treated, has been accepted in the December 2011 base case.

Gold equivalent ounces are defined as metal (including copper) converted to an amount of gold in ounces, based on accepted gold and other metal prices, i.e. the accepted total value of the metal based on its weight and value thereof divided by the accepted value of one troy ounce of gold.

Mineral Resource classification (gold)

Tonnes (Mt) Gold grade (g/t) Gold (‘000 oz)

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Open pit

Measured 98.0 44.1 30.8 0.9 1.0 0.9 2,717 1,411 938

Indicated 44.9 100.0 117.7 0.6 0.7 0.8 882 2,331 2,919

Inferred 0.8 2.2 12.5 0.3 0.5 0.5 9 38 201

Total open pit 143.8 146.3 161.0 0.8 0.8 0.8 3,608 3,780 4,058

Surface stockpiles

Measured 7.9 7.8 7.5 1.3 1.3 1.3 339 335 324

Total surface stockpiles 7.9 7.8 7.5 1.3 1.3 1.3 339 335 324

Grand total 151.7 154.1 168.5 0.8 0.8 0.8 3,946 4,115 4,382

Mineral Resource classification (copper)

Tonnes (Mt)1 Copper grade (%) Copper (Mlbs)

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Open pit

Measured 97.5 44.0 30.5 0.5 0.5 0.5 981 530 331

Indicated 44.5 99.8 117.2 0.4 0.4 0.4 387 903 1,117

Inferred 0.8 2.1 12.3 0.3 0.4 0.3 6 18 92

Total open pit 142.9 145.9 160.0 0.4 0.5 0.4 1,373 1,451 1,540

Surface stockpiles

Measured 1.2 1.2 1.2 0.5 0.5 0.5 13 13 13


Grand total 144.1 147.1 161.2 0.4 0.5 0.4 1,386 1,464 1,553

1 These tonnes are repeated in the gold statement, but exclude the gold only bearing oxide tonnes.

Mineral Resources (gold including copper as gold equivalents)Dec 2011 (’000 oz)

Dec 2010 (’000 oz)

June 2010 (’000 oz)

Gold 3,946 4,115 4,382

Copper as gold equivalent 3,729 3,992 4,272

Grand total 7,676 8,107 8,654

Mineral Resources are reported as in situ within pit shells and are inclusive of those Mineral Resources which have been modified to produce Mineral Reserves. The Measured, Indicated

and Inferred oxide and sulphide Mineral Resource estimate has been calculated within the diorite intrusion above 3,300 mRL.

Vie

w o

f the

sur

ge ta

nk in

the

proc

essi

ng p

lant


Modifying factors ¨ Mineral Resources and Mineral Reserves are quoted at an

appropriate economic NSR* cut-off with costs and tonnages and grades based on the resource block model. They also include estimates of any material below the NSR cut-off required to be mined to extract the complete pay portion of the Resource;

¨ Mineral Resources and Mineral Reserves are quoted as at 31 December 2011;

¨ Unless otherwise stated, all Mineral Resources and Mineral Reserves are quoted as 100% and are not attributable with respect to ownership;

¨ All Mineral Reserves are quoted in terms of run-of-mine (RoM) grades and tonnages as delivered to the metallurgical processing facilities;

¨ Mineral Reserve statements include only Measured and Indicated Mineral Resources, modified to produce Mineral Reserves as contained in the LoM plan;

¨ Mineral Resources and Mineral Reserves undergo both internal and external audits during the year and any issues identified are rectified at the earliest opportunity – usually during the current reporting cycle

* Net smelter return (NSR) is defined as the return from sales of concentrates, expressed in US$/t, i.e.: NSR = (Au price – Au selling cost) x Au grade x Au recovery + (Cu price – Cu selling cost) x Cu grade x Cu recovery.

Mineral Resource parameters

Dec 2010

Dec 2011

Gold price US$/oz 1,100 1,450

Copper price US$/lb 3.0 3.9

NSR cut-off for mill feed US$/t 16.04 18.01

Cut-off for oxide ore g/t 0.4 0.4

Mineral Reserve parameters

Gold price US$/oz 1,000 1,300

Copper price US$/lb 2.72 3.50

NSR cut-off for mill feed US$/t 16.04 18.01

Strip ratio waste: ore 0.63 0.75

Plant Recovery Factor (Au) – Mixed

% 54 51

Plant Recovery Factor (Cu) – Mixed

% 69 61

Plant Recovery Factor (Au) – Supergene

% 68 67

Plant Recovery Factor (Cu) – Supergene

% 85 82

Plant Recovery Factor (Au) – Hypogene

% 74 70

Plant Recovery Factor (Cu) – Hypogene

% 90 88

Processing throughput per year

Mtpa 6.2 6.6

Dilution % 0 0

Cer

ro C

oron

a pl

ant a

t nig

ht

11

Grade tonnage curves

250

200

150

100

50

0

1.0

0.8

0.6

0.4

0.2

0.00 5 10 15 20 25

Cut-off net smelter return (US$/t)

Sulphide Mineral Resources

A

vera

ge g

rade

abo

ve c

ut-o

ff –

Au

(g/t

)

Ave

rage

gra

de a

bove

cut

-off

– C

u (%

)

To

nnes

(mill

ions

)

Mineral Reserve classification (gold)

Tonnes (Mt) Gold grade (g/t) Gold (‘000 oz)

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Open pit

Proved 85.3 41.0 23.7 0.9 1.0 1.0 2,512 1,357 788

Probable 23.5 44.1 64.3 0.7 0.9 0.9 513 1,267 1,910

Total open pit 108.8 85.1 88.0 0.9 1.0 1.0 3,025 2,623 2,698

Surface stockpiles

Proved 1.2 1.2 1.2 1.2 1.3 1.3 47 48 48


Grand total 110.0 86.3 89.2 0.9 1.0 1.0 3,072 2,672 2,746

Mineral Reserve classification (copper)

Tonnes (Mt) Copper grade (%) Copper (Mlbs)

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Dec 2011

Dec 2010

June 2010

Open pit

Proved 85.3 41.0 23.7 0.5 0.6 0.5 897 507 275

Probable 23.5 44.1 64.3 0.4 0.5 0.5 215 444 687

Total open pit 108.8 85.1 88.0 0.5 0.5 0.5 1,112 951 963

Surface stockpiles

Proved 1.2 1.2 1.2 0.5 0.5 0.5 13 13 13


Grand total 110.0 86.3 89.2 0.5 0.5 0.5 1,126 965 976

Mineral Reserves (gold including copper as gold equivalents)Dec 2011 (’000 oz)

Dec 2010 (’000 oz)

June 2010 (’000 oz)

Gold 3,072 2,672 2,746

Copper as gold equivalent 3,031 2,624 2,533

Grand total 6,103 5,295 5,278

2.5

2.0

1.5

1.0

0.5

0.0

2.5

2.0

1.5

1.0

0.5

0.00 0.2 0.4 0.6 0.8 1.0 1.41.2

Cut-off grade (g/t)

Oxide Mineral Resources

A

vera

ge g

rade

abo

ve c

ut-o

ff –

Au

(g/t

)

To

nnes

(mill

ions

)


Mineral Resources and Mineral Reserves reconciliation year-on-year

Factors that affected the Mineral Resource reconciliation:

¨ Decrease resulting from mining depletion;

¨ An increase in metal prices;

¨ An updated resource model; and

¨ An increase in the NSR cut-off as a result of an increase in overall cost and sustaining capital.

Factors that affected the Mineral Reserve reconciliation:

¨ Decrease resulting from mining depletion;

¨ A 30 Mt increase in the TSF design;

¨ An increase in metal prices; and

¨ New geological and resource model.

Change in gold Mineral Resources December 2010 to December 2011

Cos

ts

Gol

d (M

oz) 4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.0

Met

al p

rice

Exc

lusi

ons/

Incl

usio

ns

Sto

cks

Min

edde

plet

ion

Res

ourc

em

odel

ling

Dec

embe

r20

10

Dec

embe

r20

11

4.10.3

0.10.2

0.10.1

0.0 4.0

1,600

1,400

1,200

1,000

800

600

400

200

0

Change in copper Mineral Resources December 2010 to December 2011

Cop

per

(Mlb

)

Met

al p

rice

Exc

lusi

ons/

Incl

usio

ns

Sto

cks

Min

edde

plet

ion

Cos

ts

Res

ourc

em

odel

ling

Dec

embe

r 2

010

Dec

embe

r20

11

1,464102

3976

2962 0 1,386

Change in gold Mineral Reserves December 2010 to December 2011

Met

al p

rice

Cos

ts

Gol

d (M

oz) 3.5

3.0

2.5

2.0

1.5

1.0

0.0

Incl

usio

ns/

Exc

lusi

ons

Sto

cks

Min

e de

plet

ion

Mod

ellin

g

Dec

embe

r20

10

Dec

embe

r20

11

2.70.3

0.1 0.1

0.0

0.5

0.0 3.1

1,200

1,000

800

600

400

200

0

Change in copper Mineral ReservesDecember 2010 to December 2011

Cop

per

(Mlb

)

Mod

ellin

g

Cos

ts

Incl

usio

ns/

excl

usio

ns

Sto

cks

Min

ede

plet

ion

Met

al p

rice

Dec

embe

r20

10

Dec

embe

r20

11

965

106

22 35 12

223

0 1,126

Mineral Reserve sensitivityImproved Mineral Resources and Mineral Reserves potential is influenced by increased commodity prices, but is constrained by the size of the tailings storage facility (130 Mt).

The sensitivities are not based on detailed depletion schedules and should be considered on a relative and indicative basis only.

Note:Cerro Corona is still tonnage constrained due to the capacity of its tailings facility. Adoption of possible TSF expansion opportunities will provide the mine with future upside potential.

Managed Mineral Reserve Sensitivity

6.1

(-10%)

6.1

(-5%)

6.1

(+5%)

6.1

(+10%)

6.1

(+25%)

6.1

1,300(Base)

8.0

6.0

4.0

2.0

0

Gold price (US$/oz)

Au+

Cu

as A

u-E

q (M

oz)

13

10. Regulatory codes

SAMRECThis technical statement has been prepared in compliance with the South Africa Code for the Reporting of Exploration Results, Mineral Resources and Mineral Reserves (2007 SAMREC Code).

JSEThis technical statement has been prepared in compliance with the Listings Requirements of the JSE Limited, South Africa (JSE), specifically Section 12.

Sarbanes-Oxley ActThe Mineral Resources and Mineral Reserves are underpinned by an appropriate Mineral Resource management process and protocol to ensure adequate corporate governance in respect of the intent of the Sarbanes-Oxley Act.

EnvironmentalCerro Corona has an environmental management team which is supported by specialists from the regional corporate offices in Johannesburg and Perth. The systems, procedures, training, etc. are at international leading practice levels.

11. Competent Persons

Competent Persons

Eddie Garcia: Mineral Resources ManagerMine Engineering, MBA, SAIMM (704963), SME (4028357), CIP (109603), Pontificia Universidad Católica del Perú. Mr Garcia has 14 years’ experience in mining engineering and three years in business planning. Mr Garcia is responsible for the Mineral Resources and Mineral Reserves at Cerro Corona and compilation of the CPR.

Julian Misiewicz: Consulting GeologistBSc (Hons) Geology, MSc Geology. Mr Misiewicz is a Fellow of the Society of Economic Geologists (SEG 541613). He has 33 years’ experience in the mineral exploration and mining industry.

Don Ross-Watt: Consulting Mine and Mining EngineeringBSc Mining Engineering, BSc Civil Engineering, MEng Mineral Economics, ECSA Professional Engineering (82190), SAIMM (19412). Mr. Ross-Watt has 39 years’ experience in the mining industry.

Hugo Solis: Chief EngineerMine Engineering, CIP (77973), Universidad Nacional Mayor de San Marcos. Mr Solis has 16 years’ experience in surface and underground mining operations. Mr Solis has completed his MBA studies at Centrum Católica.

Hugo Rios: Senior Resource ModellerGeological Engineering, Universidad Nacional de Ingeniería, MBA Centrum Católica, CIP (92165), SEG (672559). Certified in applied geostatistics by the University of Alberta. Mr Rios has over 10 years’ experience in exploration, mining and resource modelling. Currently, he is responsible for the Resource Department at Cerro Corona Mine.

Angel Uzategui: Senior Mine GeologistGeological Engineering, CIP (12337), Universidad Nacional San Agustín. Mr Uzategui has over 18 years’ experience in surface and underground mining operations and exploration, he is responsible for the Grade Control Department and Structural and Geological interpretation at Cerro Corona Mine.

Internal technical reviews have been conducted by the Competent Persons as listed, who are full-time employees of Gold Fields Limited.

Hau

ling

ore

from

the

open

pit.


Post Incumbent Qualifications Years Key responsibilities

General Manager Manuel Diaz Metallurgical Engineer 26 Responsible for the overall strategic direction, leadership and management

Strategic Planning Manager

Alberto Cardenas Civil Engineer, MBA 17 Strategic direction and member of the Task Team that support IGTRB

Chief Financial Officer Rodolfo Michels BS in Business Administration 43 Financial management, reporting and compliance

Operations Manager Gonzalo Eyzaguirre

Mine Engineer, MBA 17 Mine operations process plant and tailing construction

Process Manager Ronald Diaz Metallurgical Engineer 16 Mineral processing and metallurgy

Environmental Manager

Luis Alberto Sanchez

MSc Environmental Services Mechanical Engineer

28 Environmental management

12. Key technical staff

Cop

per-

gold

flot

atio

n co

ncen

trat

e lo

aded

for

ship

men

t

Project Boundary . . . . . . . . . . . .

Open pit . . . . . . . . . . . . . . . . . . . .

Tailings Dam . . . . . . . . . . . . . . . .

Waste Dump . . . . . . . . . . . . . . . .

Quarry . . . . . . . . . . . . . . . . . . . . . .

Top Soil Dump . . . . . . . . . . . . . .

Blankets . . . . . . . . . . . . . . . . . . . .

Reference

Project Boundary . . . . . . . . . . . .

Open pit . . . . . . . . . . . . . . . . . . . .

Tailings Dam . . . . . . . . . . . . . . . .

Waste Dump . . . . . . . . . . . . . . . .

Quarry . . . . . . . . . . . . . . . . . . . . . .

Top Soil Dump . . . . . . . . . . . . . .

Blankets . . . . . . . . . . . . . . . . . . . .

Reference Cerro Corona MinePlan showing mine infrastructure as at 31 December 2011

Oxide Stockpile . . . . . . . . . . . . .

Office. . . . . . . . . . . . . . . . . . . . . . .

Rivers . . . . . . . . . . . . . . . . . . . . . .

Roads . . . . . . . . . . . . . . . . . . . . . .

Powerline . . . . . . . . . . . . . . . . . . .


13. Brief history

The history of Cerro Corona

1979: Exploration by BRGM identified porphyry-style mineralisation in the Cerro Corona area.

1984 – 2003: Mina Carolina intermittently exploited lead-zinc-silver mantos and veins in Hualgayoc district.

1992 – 1993:Sampling by Gubbins Group identified gold mineralisation in leached cap of Cerro Corona deposit. Cu Au porphyry mineralisation discovered through drilling of nine diamond core holes and completion of exploration adit into mineralised zone.

1994 – 1996:

Cerro Corona optioned by Barrick. 140 reverse circulation drill holes totalling 9,476 metres and 118 diamond core holes totalling 35,694 metres completed in Cerro Corona deposit area. Draft feasibility study completed by Kilborn indicating Mineral Reserves of 6.85 Mt of oxide ore at 1.34 g/t Au and 84 Mt of sulphide ore at 1.02 g/t Au and 0.58% Cu.

1997 – 1998:Cerro Corona optioned by RGC Limited. Six diamond core holes totalling 2,760 metres completed. Preliminary feasibility study completed by Fluor in 1998 estimated Mineral Reserves at 6.98 Mt of oxide ore at approximately 1.3 g/t Au and 133 Mt of sulphide ore at 0.91 g/t Au and 0.52% Cu.

2000 – 2001:Minproc draft feasibility study estimated sulphide Mineral Reserves at 65.2 Mt at 1.14 g/t Au and 0.61% Cu. However this was followed immediately by a further study, which indicated a Mineral Reserve of 95 Mt that was used in the due diligence.

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.

2004 – 2005:Gold Fields completed surface land acquisition, project engineering and design work, environmental impact assessment, pit dewatering investigations, remapping of surface geology, relogging of prior drill core, check assaying investigations and updated Mineral Resource and Mineral Reserve estimates.

2006:Environmental impact assessment approved on 2 December 2005. Purchase transaction for the Cerro Corona Project completed in January 2006. Mine construction commenced in May 2006.

2007: Las Gordas tailing dam construction commenced in May 2007. Rhyolite quarry commenced mining.

2008: Cerro Corona moved into production in August 2008 when the process plant started to operate.

2009: 139 koz of gold, 41 k/tonne of copper and 394 koz of equivalent oz were produced between July 2009 and June 2010 in Cerro Corona.

2010: A 5,916 metre in-fill drilling programme was conducted during the first half of the year.

2011:

A 9,449 metre in-fill drilling programme was completed to improve the resource model.

Gold Fields Corona (BVI) Limited a wholly owned subsidiary of Gold Fields Limited, increased its economic interest in Gold Fields La Cima S.A. from 80.7% to 98.5%.


Elev (Z)

+3900

+3800

+3700

+3600

+3500

+3400

North (Y)

+9252800

+9252600

+9252400

+9252200

+9252000

+9251800

762

700

762

800

762

900

763

000

+763

100

+763

200

+763

300

+763

400

+763

500

+763

600

+763

700

+763

800

Cerro Corona Mineral Resource and Mineral Reserve Classification

EXPLORATIONRESULTS

MINERALRESERVES

MINERALRESOURCES

Reported as in situmineralisation estimates

Consideration of mining, metallurgical, economic, marketing, legal,environmental, social and governmental factors (the ‘modifying factors’)

Gold 151.7 Mt @ 0.8 g/t 3.9 Moz Copper 144.1 Mt @ 0.4% 1,386 Mlbs

Gold 110.0 Mt @ 0.9 g/t 3.1 Moz Copper 110.0 Mt @ 0.5% 1,126 Mlbs

Gold 23.5 Mt @ 0.7 g/t 0.5 Moz Copper 23.5 Mt @ 0.4% 215 Mlbs





Reported as mineableproduction estimates

Incr

easi

ng le

vel o

f geo

scie

ntifi

c kn

owle

dge

and

confi

denc

e

MEASURED PROVED

PROBABLEINDICATED

INFERRED

3D model of the Cerro Corona ore body

Notes

Cer

ro C

oron

a m

ill

This Technical Short Form Report (“the Report”) contains information as at 31 December 2011 (“the Effective Date of this Report”). The statements and information set out in this Report speak only as of the Effective Date of this Report. Shareholders and other interested and affected parties are therefore urged to review all public disclosures made by Gold Fields after the Effective Date of this Report, as some of the information contained in the Report may have changed or have been updated. Gold Fields does not undertake any obligation to update publicly or release any revisions to statements and information set out in this Report to reflect events or circumstances after the Effective Date of this Report or to reflect the occurrence of unanticipated events, unless obliged to do so pursuant to law or regulation. In such event, Gold Fields does not undertake to refer back to any information contained in this Report.


“If we cannot mine safely, we will not mine”

Gold Fields Safety Value

Registered Office South Africa:150 Helen RoadSandownSandton, 2196 JohannesburgGautengPrivate Bag X30500Houghton, 2041 South Africa

Website: http://www.goldfields.co.za Telephone: +27 (0) 11 562 9700Facsimile: +27 (0) 11 562 9838

Cerro Corona Mine · The mining rights owned by Cerro Corona cover an area of 2,971 ha. The surface...

Documents

Transcript of Cerro Corona Mine · The mining rights owned by Cerro Corona cover an area of 2,971 ha. The surface...