View
1
Download
1
Category
Preview:
Citation preview
Tarkwa Gold MineTechnical Short Form Report31 December 2012
1. OverviewGold Fields Ghana Limited (GFGL) was incorporated in Ghana in
1993 as the legal entity holding the Tarkwa concession mining
rights. Gold Fields Ghana Holdings Limited holds 90% of the
issued shares of GFGL, after acquiring the indirect 18.9% of the
issued shares belonging to IAMGold and its affiliates. The
government of Ghana holds a 10% free carried interest, as
required under the mining law of Ghana. The Tarkwa Gold Mine
operates under seven mining leases covering a total area of
approximately 20,825 hectares.
The Tarkwa Gold Mine is located in south-western Ghana near
the southern end of what is commonly referred to as the Tarkwa
Basin and is 300 kilometres by road west of Accra, the Ghanaian
capital. The mine is easily accessible with an established
infrastructure.
The open pit surface operation exploits narrow, tabular auriferous
conglomerates similar to those mined in the Witwatersrand Basin
of South Africa. Mining is currently taking place from four pits –
Pepe-Mantraim, Teberebie, Akontansi and Kottraverchy. At
present the mine uses a conventional Carbon-In-Leach (CIL) plant
and a Heap Leach facility. In the 12 months ended December
2012, Tarkwa produced 719 koz of gold from the milling and heap
leach operations at a cash cost of US$673/oz.
The extended LoM is primarily due to the inclusion of the South
Heap retreatment through the CIL plant at the end of life. The
North Heap facility will continue until it becomes uneconomical,
which is currently estimated to be 2014/5. Various alternative
processing options are currently being investigated, including an
expansion of the existing CIL plant and/or the construction of an
applicable, discrete CIL/CIP facility. Alternatively the mine will
revert to the CIL option only, which currently produces the best
cash returns in the medium term and extends the Life of Mine
(LoM) to 2036.
This Technical Short Form Report reflects the latest LoM plan input
parameters, coupled with an updated Mineral Resource and
Mineral Reserve statement, as at 31 December 2012.
All Mineral Resource and Mineral Reserve figures reported are
managed unless otherwise stated, and Mineral Resources
are inclusive of Mineral Reserves.
SaSaSaSaaSaaaaSalilillilililieneneneneneenent tttt t fefefefefeffefeeatatatatatatatttturururururururesesesesesses
������� MiMiMiMiMMiMiMineneneneeerararararararall llll ReReReRReReReeesososoosooosourururururuu cecececececececesss s ss atatatatata 1 1 11 4.4.4.4.44 66 6 6 66 MoMoMoMoMoMoMoz zz z z (i(i(((i(((incncncncnclulululululuddidididdingngngnggng
ununununu dedergrgrggrororrorounununununund)d)d)d)d)).....
����� MiMiMiMiMiMiMiineneneneeen rararararaall l ll l ReReReReReeeeR seseseseseseservrvrvrvrvvrvesesesesessses a a aa aat t tt 1010101000.1.1.1.1.1 M M M MMMMozozozozozoz..
������� SoSoSoSoSoSoSooS lillililil d d d d ddd d ananananananannchchchchchchoroororororoo fff f f ffoororororor g gg gg gggrororororor wtwtwtwtwtw h h h hhh inininininn t t t ttheheheheheh W WW WW WWesesesesesesest t t t tt AfAfAfAfAfAfAAfririririririricacacacacaac
ReReReReReReegigigigiggigiononononnonononoo .....
�������� OwOOwOwOwOwOwOwneneneenennen r-r-r-r-r-r-opopopopopopopopererererereree atatattataatedededdededd, ,, , hihihihihih ghghghghghghg -v-v-v-vv-vvololololololumumumumumumme,e,e,e,e,ee,e g g g g g g ggrarararararararadededededed -d-d-d-ddddriririririveveveveeevev n n n nnnn
sususususuuurfrfrfrfrfrfr acacacacacaaceeeeee ee opopopopopopopoperereerererre atatatatatatatatioioioioioon.nn.n.n.nn
��������� AAA A AAAA wewewewwewewewew llllllllllll-u-u-uu-undndndndndndndndererereerststststttoooooooooooooooodd d d dd d d prprprprprprpredededededeee icicicicicictatatatatatataablblblblbbb e e e eee ororororororro e e e e eee e boboobobobob dydydydydydyd ..
����� FoFoFoFoFocucucucus s s ononon m m mmmmaaaiaaaaaaa ntaining hhhhhhhigigigigigiigigigh h h hh mimimimiminininininnin ngngngnggngg fl flfl fl flflfleeeeeeeeet t tt
efefefee ficficficfifi ieieieieencncncncncieieieeees.ssssssss
�������� LiLLiLiLiLiLiifefefefefefe o o o oo off fff f MiMiMiMiMMiMMiM nnenenennenn e e eeeextxtxttxtxteeeneneneneendsddsdsdsdsdsd tt tttto o o ooo 202020220203636363363636 ( ( ( (((24242424242424 y y y yy yyeaeaeaeaeaeaeaearsrsrsrsrsrsrs).).).).).)
Geographic locationTarkwa locality plan with mining lease magnified
1Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012 �
Page head
Geographic location IFC
1. Overview IFC
2. Asset fundamentals Page 2
3. Operating statistics Page 3
4. Geological setting and mineralisation Page 4
5. Mining Page 6
6. Projects Page 7
7. Mineral processing Page 8
8. Sustainable development Page 9
9. Mineral Resources and Mineral Reserves Page 10
10. Competent Persons Page 13
11. Key technical staff Page 14
12. Brief history Page 17
Cover image: Mining operations at Teberebie
Note: For abbreviations refer to page 27 and for glossary of
terms refer to page 28 – “Mineral Resources and Mineral
Reserves Overview 2012”.
��Aerial view of sustainable rehabilitation programme at Tarkwa
Contents
gold d osits and is a remier
West Africa is host to world-class West Africa is host to world-class
gold deposits and is a premier gold deposits and is a premier
mining destination. Gold Fieldsmining destination. Gold Fields
has a strong presence in the regio has a strong presence in the region has a strong presence in the region
and Tarkwa is ideally positioned to and Tarkwa is ideally positioned to and Tarkwa is ideally positioned to
support the Gold Fields vision: support the Gold Fields vision: support the Gold Fields vision:
“To be the global leader in “To be the global leader in
i bl ld i i ”sustainable gold mining.”sustainable gold mining.”
2 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
2. Asset fundamentals
Prepared by Gold Fields Limited in compliance with the South African Code for the Reporting of Exploration
Results, Mineral Resources and Mineral Reserves (2007 SAMREC Code)
Effective date 31 December 2012
Source of information This Technical Statement is a summary of the December 2012 Tarkwa Competent Persons Report
(CPR)
Personal inspection Personal inspection is conducted by the Competent Persons as listed, who are full-time
employees of Gold Fields Limited
Independent review Information reported in this declaration is as reviewed by internal consultants as at 31 December
2012. Tarkwa has been informed that the review identified no material shortcomings in any
process by which the Mineral Resources and Mineral Reserves were evaluated
General location Tarkwa is located in south-western Ghana approximately 300 kilometres by road west of Accra,
the capital, at latitude 5° 15’ N and longitude 2° 00’ W. The Tarkwa Gold Mine is located four
kilometres west of the town of Tarkwa with good access roads and an established infrastructure.
The mine is served by a main road connecting to the port of Takoradi some 60 kilometres to the
south on the Atlantic coast
Climate Although there may be minor disruptions to operations during the wet season, there are no
long-term constraints on production due to climate
Licence status and
holdings
The Tarkwa mine operates under mining leases covering a total area of approximately
20,825 hectares. Five mining leases, dated 18 April 1997, cover the Tarkwa property, while two
mining leases, dated 2 February 1988 and 18 June 1992 respectively, cover the Teberebie
property. The Tarkwa concession mining leases expire in 2027 and the Teberebie property mining
leases expire in 2018. Application for an extension of the mining leases will be applied for at the
appropriate time, but there is no reason to expect that these will not be granted. All necessary
statutory mining authorisations and permits are in place for the Tarkwa Mine Lease and GFGL is
entitled to mine all material falling within the lease
Operational
infrastructure
The existing surface operation currently exploits narrow auriferous conglomerates, similar to those
mined in the Witwatersrand Basin of South Africa. Following a feasibility study in 2004, the deposit
is mined on an owner-operated basis, and processing from 2004 to December 2012 utilised a
conventional CIL plant as well as a heap leach facility
Deposit type The open pit surface operation currently exploits the tabular auriferous conglomerates from four
open pits – Pepe-Mantraim, Teberebie, Akontansi and Kottraverchy
Life of Mine (LoM) It is estimated that the current Mineral Reserves will be depleted in 2036 (24 years)
Environmental/Health
and Safety
Tarkwa retained its ISO 14001:2004 environmental management system and certification following
an external audit during 2012. The mine also retained its full compliance to the International
Cyanide Management Institute (ICMI) Cyanide Management code
Reporting codes Gold Fields reports its Mineral Resources and Mineral Reserves in accordance with the 2007
SAMREC Code, the South African Codes for the Reporting of Mineral Asset Valuation (2009
SAMVAL Code) and other relevant international codes such as the United States Securities and
Exchange Commission (SEC) Industry Guide 7, the Joint Ore Reserves Committee (JORC 2012)
Code and the National Instrument (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 Sarbanes-Oxley Act
Transporting ore In pit fuel farm Water treatment plant Aerial view of metallurgical plant
3Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012 �
3. Operating statistics
Historic performance Units
Dec
2012
Dec2011
Dec20101
June2010
June2009
Open pit mining
Total mined kt 138,238 117,156 67,063 134,131 132,585
– Waste mined kt 116,330 94,927 56,008 111,051 109,906
– Ore mined kt 21,908 21,876 10,840 22,716 21,273
Mined grade g/t 1.3 1.2 1.2 1.2 1.2
Strip ratio (tonnes) waste:ore 5.3 4.4 5.2 5.2 5.1
Processing
Total tonnes kt 22,910 23,138 11,496 22,716 21,273
– Mill tonnes kt 11,600 11,426 5,639 11,182 7,733
– Heap leach tonnes kt 11,310 11,713 5,857 11,634 13,540
Combined head grade g/t 1.1 1.2 1.0 1.0 1.1
– Mill head grade (CIL) g/t 1.4 1.4 1.4 1.4 1.4
– Heap leach head grade g/t 0.8 0.9 0.9 0.9 0.9
Combined yield g/t 1.0 1.0 1.0 1.0 0.9
Plant recovery
factor
Mill % 97 97 97 97 97
Heap leach % 61 61 65 70 68
Gold produced
Total gold productionkoz 719 717 362 721 612
kg 22,358 22,312 11,261 22,415 19,048
– Mill koz 540 518 261 503 314
– Heap leach koz 179 199 101 218 299
Gold sold koz 719 717 362 721 612
Financials
Operating cost US$/oz 688 608 575 521 523
Total cash cost UUS$/oz 673 556 562 536 521
Capital expenditure US$ million 260 219 117 149 201
Notional cash expenditure (NCE) US$/oz 1,049 913 889 743 881
General
Total employees costed (TEC) number 4,175 4,024 4,153 4,377 4,107
Mineral Reserves Mt 293.3 264.8 235.3 244.2 270.0
Mineral Reserves Head Grade g/t 1.1 1.2 1.2 1.3 1.2
Mineral Reserves Moz 10.1 10.3 9.3 9.9 10.7
Expected Life of Mine years 242 13 12 12 13
1 Figures shown represent the six months to 31 December 2010.2 Extended due to the inclusion of retreatment of South Heap Leach at the end of the LoM.
Rounding off of figures presented in this report may result in minor computational discrepancies. Where this occurs it is not deemed significant.
Open pit mining operations
4 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
4. Geological setting and mineralisation
The Tarkwa ore bodies are located within the Tarkwaian
System, which forms a significant portion of the stratigraphy
of the Ashanti Belt in southwest Ghana. The Ashanti Belt is
a north-easterly striking, broadly synclinal structure made
up of Lower Proterozoic sediments and volcanics underlain
by the metavolcanics and metasediments of the Birimian
System. The contact between the Birimian and the
Tarkwaian is commonly marked by zones of intense
shearing and is host to a number of significant shear-hosted
gold deposits.
The Tarkwaian unconformably overlies the Birimian and is
characterised by lower intensity metamorphism and the
predominance of coarse-grained, immature sedimentary
units.
Local geologyThe local geology at Tarkwa is dominated by the Banket
Series, which can be further subdivided into a footwall and
hangingwall barren quartzite, separated by a sequence of
mineralised conglomerates and pebbly quartzites.
The stratigraphy of the individual quartzite units is well
established, with auriferous reefs interbedded with barren
immature quartzites. The units thicken to the west and
current sedimentological parameters indicate a flow from the
east and north-east. Structurally, the Tarkwaian belt has been
The Tarkwa operation exploits narrow auriferous conglomerates, similar to those mined in the Witwatersrand Basin of South Africa and currently mines from four open pits – Pepe-Mantraim, Teberebie, Akontansi and Kottraverchy.
subject to moderate folding, and at least five episodes of
deformation are recognised. The original deposition occurred
in a district basin environment with associated low to steep
angle normal faulting. Subsequent compression and folding
led to the development of thrust faults and inversion of
previous normal faults. The final stages involved further
thrusting in a southwest direction.
Sedimentological studies of the detailed stratigraphy within
individual A and A footwall reef units have led to the
recognition of both lateral and vertical
facies variations. The modelling of these
has resulted in the recognition of a
cycle of events from initial channel
formation and rapid down-cutting of the
central channel, through a period of
uplift and reworking. Finally, a period of
meandering channel bars and flow
reduction led to the development of
low-grade conglomerates with silty
interbeds. The period of uplift and
reworking has been recognised as
being the principal episode of gold
deposition and concentration within
these reefs. The style of sedimentation
in the C, E and G reefs differs from that
of the channelised, incised A reefs to a
more localised sheet-flood-dominated
alluvial fan deposit.
The mineralised and potentially
economic conglomerate reefs are
identified below; from the base upwards
(younging):
�� �AFc – up to 3 metres thick, only
occurs in the west and subcrops
against the A1 in the east. Well
sorted with rounded clasts of
quartzite and visible gold;
Geology of south-western Ghana
Takoradi
Group Series Thickness (m) Lithology
Tarkwaian
(youngest) Huni 1,370
Quartzites, minor
phyllites
Tarkwa
Phyllite 120 – 400
Chloritic and sericitic
phyllites and schists
Banket 120 – 160
Quartzites, grits and
conglomerates
Major
unconformity � Kawere 250 – 700
Quartzites, grits and
conglomerates
Birimian (oldest) Birimian
Meta-volcanics,
volcaniclastics and
sediments
5Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012 �
The current diamond drilling programme is guided by the
unconstrained Whittle® pit optimisations, which indicate the
potential for the economic extraction of pay shoots down-dip in
some parts of the current pits. The increase in resource gold
price to US$1,650/oz has resulted in an infill down dip diamond
drilling programme to increase resource definition. This will also
upgrade the Mineral Resource category ahead of mining and
provide detailed information for assessment of alternative select
mining cuts of the reef packages. Processing of the completed
boreholes is currently in progress.
�� A1 – between 2 and 7 metres thick,
moderately to poorly sorted
conglomerate and thin quartzites
with occasional visible gold;
�� A3 – up to seven metres thick,
moderately sorted thin
discontinuous conglomerate lenses
within a package of cross-stratified
quartzites, visible gold is rare;
�� B2 (or B) – up to three metres thick,
very coarse quartzites with thin lags
of subrounded pebble conglomerate
in the Akontansi Central area. In the
other areas it is poorly developed
and not economically extractable;
�� CDE – up to eight metres thick and
can be subdivided into the lower C
reef and upper E reef, both of which
are conglomeratic and are separated
by the D reef quartzite;
�� F2 – a variably developed polymictic gravel up to two
metres thick, essentially a marker horizon, except in the
east where it carries low grades; and
�� G – varies from a 2 to 6-metre thick poorly-sorted
conglomerate with clasts of quartzite and phyllite.
Exploration and resource definition drillingThe bulk of the Tarkwa open pit palaeoplacer Mineral Resource
has been drilled to the Measured and Indicated Mineral
Resource categories at current costs and a gold price of
US$1,650/oz. Tarkwa is now a mature mine with the focus
having shifted from exploration to optimising the extraction of
the current Mineral Resource.
Exploration drilling and expenditure:
31 December 2012 31 December 2011
Operation
Metres
drilled
US$
(million)
Metresdrilled
US$(million)
Tarkwa Gold Mine 13,529 3.720 5,588 0.448
Exclusive of grade control drilling except where it is included in the capital budget.
Stratigraphic profile of the Tarkwa ore body
Surface geology and infrastructure
6 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
The mine is owner-operated and has its own load and haul
fleet of 15 excavators, which range from 120 to 600 tonnes.
The haul fleet includes 51 dump trucks with a payload of
146 tonnes, eight dump trucks with a payload of 240 tonnes
and 17 dump trucks with a payload of 90 tonnes. The load
and haul fleet are supported by an ancillary fleet consisting of
dozers, graders, water carts and compactors. Twenty-four
owner-operated drill rigs are used for blast hole drilling.
Maintenance of the Caterpillar fleet is carried out by Gold
Fields Ghana Limited, while maintenance of the excavators
and blast hole rigs is carried out by contractors. In 2013,
Tarkwa plans to mine a total of 139 million tonnes of material
at a stripping ratio of 5.7:1.
Mining methodsTarkwa utilises a proven and highly selective mining
methodology. The location of the mining areas is defined
through the long-term planning process. The boundaries of
the pits are pegged out by survey and the area is cleared
of bush and topsoil, which is relocated for rehabilitation
purposes. After clearing, reverse circulation (RC) grade control
drilling is carried out, and geological models constructed. This
grade control information is used to update the short-term
plans and forecasts prior to the commencement of mining.
From the highest point in the pit, material is free dig or blasted
to the first blasting reference level. Currently fresh rock and
transitional zones are drilled and blasted in 6-metre lifts, with
excavation in 3-metre flitches.
Fifteen backhoe excavators are used to select waste from the
ore, and vice versa. This takes place along the sedimentary
horizons to an average accuracy of 30 centimetres on the
hangingwall, and 20 centimetres on the footwall of a reef. Pit
geologists and geotechnicians supervise all digging and
mineralised material is classified as either Run of Mine (RoM),
which is delivered to one of two primary crushers, or low
grade, which is stockpiled close to the primary crushers.
Waste material is hauled to the nearest waste dump.
Blasting currently utilises relatively close patterns and small
diameter holes, typically a 3.4-metre by 3.8-metre grid with
a hole diameter of 118 millimetres and a powder factor of
0.75 kg/BCM. Larger diameter holes and an increased grid
size will be utilised in the partially weathered material, while
decreased grid sizes will be utilised in harder material. The
small-diameter holes are used to preserve, as far as possible,
the integrity of the ore/waste contacts for selective mining
purposes.
Mine planning and schedulingIn general, all mine design and scheduling is undertaken
using Surpac®, Datamine®, Whittle®, Xeras®, Xpac® and
in-house computer software, together with the indirect
conditioning recoverable model (ICR). The planning cycle
commences with the ratification of key input parameters,
before producing a compliant Mineral Resource statement
that is adjusted for all Mineral Resource depletions. This is
followed by the planning process which includes a corporate
decision on macro-economic parameters, the development
of a one-year operational plan and the roll-out of the
operational plan into a LoM plan, which forms the basis of
Tarkwa’s annual Mineral Reserve declaration.
Standard software is utilised to derive the optimal pit shell
designs at a variety of cut-off grades. The detailed
engineering and design work on the optimised pit shells and
scheduling is carried out using these software packages.
A cut-off grade strategy is used in the Mineral Reserve
estimation process. The cut-off defines the ore/waste
segregation, and a cut-over grade defines mill/heap leach
segregation. A third cut-off known as the optimal cut-off/
cut-over is also derived and can be applied to increase
the grade and therefore the cash flow in the initial years of
the LoM plan. Material between the optimal cut-off/cut-over
and the process cut-off is stockpiled for treatment at the end
of the LoM.
5. Mining
Tarkwa is a large, established open pit gold mine that utilises selective surface mining
methods to optimise the extraction of the sedimentary mineral deposits.
Selective mining at Tarkwa
7Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012 �
A detailed one-year operating and capital cost budget is
developed for all operational plans and, where appropriate,
extended for the LoM production schedule. Zero-based
costing is used to formulate the one-year plan. Historic
productivity data and operating costs are utilised as the basis
from which the operational budget is benchmarked. All
capital projects are ranked and prioritised to maximise capital
efficiency and return on investment.
The North Heap facility will continue until it becomes
uneconomical, as increased hardness and reduced porosity
negatively impacts the gold recovery. Various alternative
processing options are currently being investigated, including
an expansion of the existing CIL plant and/or the construction
of an applicable, discrete CIL/CIP facility. Alternatively the
mine will revert to the CIL option only, which will result in gold
recovery rates increasing from approximately 52%, for low
porosity material treated through Heap Leach, to 97%
through the CIL plant. The extended LoM is primarily due to
adopting a CIL option only and the inclusion of the South
Heap retreatment which will be treated through the CIL plant
at the end of life.
Mining operations at Teberebie
6. Projects
Tarkwa’s assets can be best optimised through organic
growth, increased efficiency and productivity. Business
improvement is therefore core to optimising the assets and
consequently Tarkwa embarked on the TEP6 feasibility study,
following the recommendations of the Tarkwa Options
Trade-Off Study (TOTOS), which focused on delivering a
high-value strategic direction for the mine. Among these
recommendations was the installation of a conventional
milling/leach circuit, to offset the impact of increasing
hardness and declining recoveries of the ore currently being
processed through the North Heap Leach facility. Further
work is currently in progress to determine the optimum
mining and processing capacities.
Other projects that were initiated in 2012 and are planned to
be evaluated in 2013, focus on:
�� evaluating alternative waste dumping and tailings disposal
strategies, including co-disposal;
�� improvement of heavy mining equipment infrastructure to
support the expanded LoM mining fleet;
�� a scoping study to reassess if there is a realistic
opportunity for ultimate economic extraction of the
underground Mineral Resources at the mine; and
�� review options to increase CIL capacity – mini TEP6
(~2 – 5 million tonnes)
Each of these initiatives is aimed at improving the profitability
of the operation.
In pit fuel farm to improve heavy mining equipment logistics
Recent reinterpretation work over the entire tenement holding has highlighted a number of
conceptually prospective target areas. Target definition and initial drilling activities started in
2012 are on hold for 2013.
8 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
Since 1999, all ore has been sourced from open pit mining
operations and is currently processed at the 9.8 Mtpa North
Heap Leach facility and the 12.3 Mtpa CIL plant. A third
facility, the South Heap Leach facility, was closed in
December 2008, but will be processed through the CIL plant
at the end of the LoM.
The ore is a free-milling conglomerate with negligible sulphide
content. Rocks near the surface have been affected by a high
degree of weathering which is associated with increased
porosity and increased heap leach dissolution and recovery.
The North Heap Leach facility was commissioned in 1998 to
process the initial highly porous ore and the construction of
the Phase V heap leach pad was completed in 2009. As the
mine gets deeper, so the percentage of weathered ore
amenable to heap leaching decreases. This justified the
construction of the CIL plant in 2004 and its subsequent
expansion, commissioned in January 2009. The CIL milling
process provides a 97% recovery which is not possible when
using heap leaching for the harder, unweathered ore, the
percentage of which increases over the LoM.
The North Heap Leach facility employs three stages of
crushing prior to agglomeration. Post primary crushing
through a gyratory crusher, a series of overland conveyors
transport the undersize material to the agglomeration
stockpile where it joins the final product. Secondary crushing
product is fed to the tertiary hopper via a series of conveyors.
The oversize material from the upper and lower decks
(32 mm and 22 mm respectively) feed the tertiary crushers
and the discharge from the tertiary crushers is conveyed
back to the tertiary bin. The undersize material from the
tertiary screens joins the final crushing product to the
agglomeration stockpile.
The agglomeration process involves the addition of 4 kg/t of
cement to the crushed rock to bind the fine material and
produce agglomerate that remains stacked and porous on the
heap leach pads. Following agglomeration, the ore is
transferred by conveyor and stacked on the leach pads by a
stacking conveyor.
The heaps are irrigated with a cyanide solution which dissolves
the gold as it percolates through the heaps. The pregnant
solution is collected on the layer of geotextile that lines the base
of the heaps and is pumped through a series of ponds to the
adsorption/desorption/recovery (ADR) plant. Here the gold is
adsorbed onto activated carbon, removed from the carbon by
acid wash, and recovered using electro-winning. All gold
produced at the North facility is smelted at the smelt house
using diesel-fired furnaces.
The CIL process route has a gyratory crusher that feeds two
crushed ore stockpiles, each with a live capacity of 45,000
tonnes (30 hours). Underneath each stockpile is a reclaim
tunnel, with apron feeders that feed onto a conveyor belt.
These in turn feed the milling circuit, which consists of a
semi-autogenous grinding (SAG) and ball mill. Recycle
crushing is in closed circuit with the SAG mill that has 14 MW
of installed power (2 x 7,000 kW twin-drive motors). The ball
mill has 14 MW of installed power (2 x 7,000 kW twin
drive-motors) and is in close circuit
with the cyclone cluster. The milling
circuit is operated at a capacity of
1,450 tph.
The CIL circuit consists of two trains of
eight tanks in series, which are fed from
a common leach tank. The loaded
carbon passes into a 15-tonne acid
wash column. The gold is recovered
from the loaded carbon in two 15-tonne
elution circuits. Gold is recovered from
solution by electro-winning and
smelted in an induction furnace at the
CIL smelt house.
The CIL expansion project will review the optimal tonnage profile for Tarkwa, taking into
account the fleet, ore availability, metallurgical response and required stripping ratio.
7. Mineral processing
CIL plant flow diagram
Crusher pocket
Crusher
CV01CV114 CV02 CV03
CV115
CV161
Eluted carbonscreen
2 x Regeneration kilns
2 x elutioncolumn Loaded carbon
screen
Acid column
CIL 2 tanks
CIL 1 tanks
Electrowinningcells
Pregnant solutiontank
Tailingsscreens
Furnace
Tailings tank
Tailings tank
Tailings 1 storage facility
Tailings 2 storage facility
Tailings screens
3 x ThickenerCarbon sizing
screens
Scats stockpile
4 x Trash screens
Mill returntank
Process waterpond
Milldischarge
screen
Cyclones
SAG mill
Ball mill
CV162
Stockpile
CV04
Auxiliarystockpile
CV116
LoM tailings storage facility assessment
Mining asset
LoM
deposition
(Mt)
Available
capacity
(Mt)
Surplus/
(shortfall)
Mt
Capital
requirement
US$ (million)
Tarkwa 286 297 11 290
9Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012 �
8. Sustainable development8. Sustainable development8. Sustainable development
Tarkwa’s risk-based approach to safety management seeks to
control and, where possible, eliminate hazards in the working
environment. The mine strives to achieve and maintain an
outstanding health and safety performance through the
engaged participation of employees and the application of
safe, innovative processes and technologies – all within a
framework of OHSAS 18001 and full compliance.
Tarkwa’s health and safety management system has
undergone an annual comprehensive external compliance
audit since 2005 and certification has been retained to date.
The OHSAS 18001 system is aligned with Gold Fields
Limited’s Full Compliance Health and Safety Management
System, which acts as the Group standard for the
management of occupational health and safety. It aims to:
�� Eliminate all fatal accidents at all Gold Fields operations;
�� Reduce all accident rates by 50% over five years; and
�� Maintain a safe and healthy working environment at all
times through quality training, effective communication
and employee commitment.
The initiative has the broad support of all labour unions and
associations, individual employees and management. Tarkwa
operates a comprehensive employer HIV/Aids programme
comprising Informed Consent Voluntary Counselling and
Testing (ICVCT), disease prevention and health promotion
programmes. An HIV/Aids Co-ordinator is responsible for the
implementation of an HIV/Aids programme, with the full
co-operation of the employee representative bodies and
according to the international Labour Organisation and Gold
Fields Group standards. The programme incorporates
HIV/Aids awareness and training into the mine’s induction
programme for both employees and contractors. Peer
educators facilitate discussions on HIV/Aids during health and
safety meetings and provide formal counselling and training to
on-site and off-site communities. During 2011, Gold Fields
Ghana won the Global Business Coalition’s 2011 Business
Action on Health Award for Workforce/Workplace Engagement
– with a particular focus on HIV/Aids management.
Cyanide is managed under the framework of the ICMC and the
mine was certified ICMC-compliant in June 2008. The Code
requires compliance from all suppliers and transporters of
cyanide to ensure optimal safety and responsible use. The use
of cyanide on-site is strictly monitored and changes are
incorporated into operational procedures wherever necessary.
Environmental management at Tarkwa is conducted within
the framework of an ISO 14001:2004 certified environmental
management system. Tarkwa operations follow Ghanaian
environmental requirements, as administered by the
Environmental Permitting Agency (EPA), and hold the required
environmental permits. Tarkwa complies with the EPA
requirements and provides monthly monitoring returns, an
annual environmental report and an update of the
environmental management plan (EMP) at three-year
intervals. An Environmental Impact Study (EIS) was submitted
to the Ghana EPA in March 2007 for the Tarkwa expansion
project, and approved on 27 May 2007.
Tarkwa is currently awaiting its certificate from the EPA for the
period 2010 to 2013.
Blast hole drilling at Tarkwa
Safety statistics
Class Units Dec 2012 Dec 2011 Dec 2010* June 2010 June 2009
Fatalities number – 1.0 1.0 – –
Fatality rate per mmhrs – 0.10 0.10 – –
LDIFR2 per mmhrs 0.2 0.2 0.4 0.4 0.3
1For six months to December 20102Lost Day Injury Frequency Rate
Tarkwa retained its ISO 14001:2004 environmental management system and re-certification
following an external audit during 2012. The mine also retained its full compliance to the ICMI
Cyanide Management code.
10 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
9. Mineral Resources and Mineral Reserves
Stockpile tonnage and grade estimates are based on accumulations of estimated tonnage and grades trucked throughout the history of the mine, and are therefore considered to be reasonably accurate. However, the grades and tonnages are discounted by 5% for processing purposes as experience has shown that this is realistically achievable when reclaiming a stockpile. RoM stockpile tonnages were reconciled to survey volumes in December 2012. Unless otherwise stated, all Mineral Resources and Mineral Reserves are quoted as 100% and are not attributable with respect to ownership.
Mineral ResourcesMineral Resources are quoted at an appropriate in situ economic cut-off grade, with tonnages and grades based on the resource block model. They also include estimates of any material below the cut-off grade that is required to be mined in order to extract the complete pay portion of the Mineral Resource.
This declaration is based on the premise that the heap leach process at the North Heap Leach facility will be reassessed at the end of 2013 and the milling processing capacity to be reviewed and optimised.
Mineral Resource classification
Classification
Tonnes (Mt) Grade (g/t) Gold (koz)
Dec
2012
Dec 2011
Dec 2010
Dec
2012
Dec 2011
Dec 2010
Dec
2012
Dec 2011
Dec 2010
Open pit and underground
Measured 113.0 112.0 123.5 1.46 1.49 1.46 5,292 5,361 5,798
Indicated 142.0 167.5 125.1 1.24 1.24 1.29 5,665 6,694 5,186
Inferred 30.1 33.6 14.3 2.92 2.76 3.44 2,825 2,985 1,580
Total open pit and
underground 285.1 313.1 262.8 1.50 1.49 1.49 13,782 15,041 12,565
Heap leach re-treat and
stockpiles
Indicated (South Heap Leach) 56.0 – – 0.38 – – 684 – –
Measured (stockpiles) 4.1 3.4 3.3 0.74 0.76 0.72 97 83 77
Total surface stockpiles 60.1 3.4 3.3 0.40 0.76 0.72 781 83 77
Grand total 345.2 316.5 266.1 1.31 1.49 1.48 14,563 15,123 12,642
Mineral Resource classification per mining area
Area
Measured Indicated Inferred Total Mineral Resource
Tonnes
(Mt)
Grade
(g/t)
Gold
(koz)
Tonnes
(Mt)
Grade
(g/t)
Gold
(koz)
Tonnes
(Mt)
Grade
(g/t)
Gold
(koz)
Tonnes
(Mt)
Grade
(g/t)
Gold
(koz)
Open pit
Akontansi 42.5 1.32 1,807 102.5 1.18 3,876 5.3 0.94 159 150.3 1.21 5,842
Kottraverchy 17.2 1.70 939 1.8 1.27 73 – – – 19.0 1.66 1,011
Pepe/Mantraim 26.1 1.40 1,171 14.8 1.26 600 2.0 1.22 76 42.8 1.34 1,848
Teberebie 27.3 1.57 1,374 23.0 1.51 1,118 0.1 1.59 3 50.3 1.54 2,495
Total open pit 113.0 1.46 5,292 142.0 1.24 5,665 7.3 1.02 238 262.3 1.33 11,196
Underground
Akontansi – – – – – – 12.8 3.57 1,467 12.8 3.57 1,467
Kottraverchy – – – – – – 10.1 3.46 1,120 10.1 3.46 1,120
Total underground – – – – – – 22.8 3.52 2,587 22.8 3.52 2,587
Heap leach
re-treat and
stockpiles
South Heap Leach – – – 56.0 0.38 684 – – – 56.0 0.38 684
Surface stockpiles 4.1 0.74 97 – – – – – – 4.1 0.74 97
Total surface 4.1 0.74 97 56.0 0.38 684 – – – 60.1 0.40 781
Grand total 117.1 1.43 5,388 198.0 1.00 6,350 30.1 2.92 2,825 345.2 1.31 14,563
The post-depletion Mineral Resources and Mineral Reserves have decreased by 4% and 3%
respectively as a result of resource model changes and cost inputs outstripping the gold
price increase.
11Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012 �
Modifying factors
�� The Measured and Indicated Mineral Resources are
inclusive of those Mineral Resources modified to produce
Mineral Reserves;
�� All Mineral Reserves are quoted in terms of RoM grades
and tonnages as delivered to the metallurgical processing
facilities and are therefore fully diluted; and
�� Mineral Resources and Mineral Reserves undergo regular
internal and/or external audits, and any issues identified
are rectified at the earliest opportunity.
Grade tonnage curves
Open pits
To
nnes (m
illio
ns)
Avera
ge g
rad
e a
bo
ve c
ut-
off (g
/t)
0.0 0.2 0.4 0.6 0.8 1.0 1.41.2 1.6 1.8 2.0
Cut-off grade (g/t)
350
300
250
200
150
100
50
0
3.0
2.5
2.0
1.5
1.0
0.5
0
Mineral ReservesThe Mineral Reserve estimate for Tarkwa Gold Mine is based on development of appropriately detailed and engineered LoM
plans. All design and scheduling work is undertaken to an applicable level of detail by experienced engineers using mine-
planning software. The planning process incorporates appropriate modifying factors and the use of cut-off grades and other
techno-economic investigations.
Mineral Reserve statements include only Measured and Indicated Mineral Resources modified to produce Mineral Reserves
contained in the LoM plan.
Mineral Reserve classification
Classification
Tonnes (Mt) Grade (g/t) Gold (koz)
Dec
2012
Dec 2011
Dec 2010
Dec 2012
Dec 2011
Dec 2010
Dec 2012
Dec 2011
Dec 2010
Open pit
Proved 103.9 118.1 122.5 1.29 1.30 1.26 4,305 4,943 4,982
Probable 129.3 143.6 109.5 1.20 1.15 1.19 4,996 5,328 4,192
Total open pit 233.2 261.7 232.1 1.24 1.22 1.23 9,300 10,271 9,174
Surface stockpiles
Proved 4.1 3.2 3.3 0.74 0.73 0.72 97 74 75
Probable South Heap Leach 56.0 – – 0.38 – – 684 – –
Total surface stockpiles 60.1 3.2 3.3 0.40 0.73 0.72 781 74 75
Grand total 293.3 264.8 235.3 1.07 1.21 1.22 10,081 10,345 9,249
Mineral Resource
parameters UnitsDec
2012
Dec2011
Gold price US$/oz 1,650 1,450
Cut-off for heap leach g/t 0.34 – 0.70 0.248
Cut-off for mill feed g/t 0.39 0.36
Cut-off for underground g/t 2.62 – 3.27 2.62-3.27
Mineral Reserve parameters Units
Dec2012
Dec2011
Gold price US$/oz 1,500 1,300
Cut-off for heap leach g/t 0.37 – 0.77 0.276
Cut-off for mill feed g/t 0.42 0.401
Strip ratio waste:ore 6.1 5.3
Dilution (open pits) % 11 11
Mining recovery factor % 100 100
MCF % 100 100
Plant recovery factor – fresh ore % 97 97
Plant recovery factor – oxide ore % 97 97
Heap leach recovery factor % 52 61
CIL Processing capacity Mtpa 12.3 12.3
Heap leach capacity Mtpa 9.8 9.8
12 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
Mineral Reserve classification per mining area
Area
Proved Probable Total Mineral Reserve
Tonnes
(Mt)
Grade
(g/t)
Gold
(koz)
Tonnes
(Mt)
Grade
(g/t)
Gold
(koz)
Tonnes
(Mt)
Grade
(g/t)
Gold
(koz)
Open pit
Akontansi 40.6 1.19 1,551 92.1 1.15 3,403 132.6 1.16 4,954
Kottraverchy 12.1 1.49 579 0.2 1.10 7 12.3 1.48 586
Pepe/Mantraim 24.5 1.24 975 8.8 1.12 317 33.3 1.21 1,291
Teberebie 26.7 1.40 1,200 28.2 1.40 1,269 55.0 1.40 2,469
Total open pit 103.9 1.29 4,305 129.3 1.20 4,996 233.2 1.24 9,300
Spent Ore (South Heap Leach) 56.0 0.38 684 56.0 0.38 684
Surface stockpiles 4.1 0.74 97 – – – 4.1 0.74 97
Grand total 108.0 1.27 4,402 185.3 0.95 5,680 293.3 1.07 10,081
Mineral Resources and Mineral Reserves reconciliation year-on-year
Factors that affected Mineral Resource reconciliation
�� Depletion by mining (RoM and low-grade ore);
�� Changes to the Pepe-Atuabo-Mantraim-Teberebie
Resource and Akontansi models;
�� Economic factors resulting from the increase in cost
inputs that marginally outstripped the increased gold
price; and
�� Inclusion of spent ore from South Heap Leach into
Mineral Resource.
Go
ld (M
oz)
14.560.40 0.010.01
0.68
0.85
15.12
Change in Mineral ResourcesDecember 2011 to December 2012
Sp
ent
Ore
Decem
ber
20
11
Min
ed
dep
letio
n
Reso
urc
e
mo
delling
Eco
no
mic
fa
cto
rs
Oth
er
Decem
ber
20
12
16
14
12
10
8
6
4
2
0
Mineral Reserve sensitivityThe Mineral Reserve Sensitivity has been derived from the
application of the relevant cut-off grades to individual grade
tonnage curves of the optimised pit shells for the open pits.
The Mineral Reserve sensitivities are not based on detailed
depletion schedules and should be considered on a relative
and indicative basis only. The following graph indicates the
Managed Mineral Reserve sensitivity at -10%, -5%, Base
(US$1,500), +5%, +10% and +25% to the gold price.
Factors that affected Mineral Reserve reconciliation
�� Depletion by mining (RoM and low grade);
�� Increase in cost inputs marginally outstripped the
increased gold price;
�� Minor changes due to design change; and
�� Inclusion of spent ore from South Heap Leach into
Mineral Reserve at end of LoM.
Managed Mineral Reserve sensitivity
Go
ld (M
oz)
10.98
10.6810.50
10.08
9.60
9.28
(-10%) (-5%) (Base)1,500
(+5%)
Gold price (US$/oz)
(+10%) (+25%)
11.5
11.0
10.5
10.0
9.5
9.0
8.5
8.0
Go
ld (M
oz)
0.07 0.03
10.08
0.00 0.00
0.68
0.85
10.35
Change in Mineral ReservesDecember 2011 to December 2012
Sp
ent
Ore
Decem
ber
20
11
Min
ed
dep
letio
n
Reso
urc
e
mo
delling
Exclu
sio
n
Eco
no
mic
fa
cto
rs
Oth
er
Decem
ber
20
12
12
10
8
6
4
2
0
13Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012 �
10. Competent Persons
Competent Persons
Godfred Baba Avane: Mineral Resources Manager
MSc (Hons) (Geological Engineering); (MAusIMM; Registration number 309400). Mr Avane has over 17 years’ experience in
the mining industry and is the lead Competent Person, responsible for overall Mineral Resource Management for Tarkwa.
Robert van der Westhuizen; Regional Chief Strategic Planning Engineer
BSc (Hons) (Geology); MSc (Mining) (MAusIMM; Registration number 223783). Mr van der Westhuizen has 33 years’
experience in the mining industry and is responsible for the overall correctness, standard and compliance of the LoM
planning, scheduling, reserve statement and financial analysis for Tarkwa.
John A Searra: Chief Resource Geologist
BSc (Hons) (Geology); MSc (Engineering). Mr Searra has over 27 years’ experience in the mining industry and is responsible
for sampling, geology, exploration and resource estimation for Tarkwa.
Internal technical reviews have been conducted by the Competent Persons as listed, who
are full-time employees of Gold Fields Limited.
Aerial view of metallurgical complex
14 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
11. Key technical staff
Post Incumbent Qualifications Years Key responsibilities
General Manager Michiel van der
Merwe
BEng Extractive Metallurgy 16 Responsible for the overall strategic
direction, leadership and
management
Manager Mining Stephen Osei
Bempah
BSc Mining Engineering 29 Full operational management
Mineral Resources
Manager
Godfred Baba
Avane
MSc Geological Engineering 17 Mineral resource management
Financial Manager Hein Muller BCom Accounting 24 Financial reporting and compliance
Human Resources
Manager
Mohammed
Abubakari
MPA, BA Hons Economics, ACCA 17 Human resource management
Metallurgy
Manager Heap
Leach
Casper
Dzomeku
MSc Minerals Engineering, MCSM,
Exec MBA
28 Mineral processing and metallurgy
heap leach
Metallurgy
Manager CIL
George Nutor BSc Mineral Engineering 19 Mineral processing and metallurgy
CIL
Engineering
Manager –
Process
H de Beer Diploma Mechanical Engineering
Government Certificate of
Competency
29 Process engineering, logistics and
infrastructure management
Safety Manager D Pienaar NADSAM (M+3) 24 Health and safety
Environmental
Manager
Ben Addo BSc Chemistry, MSc
Environmental management
19 Environmental management
Engineering
Manager HME
A Landsberg National Higher Diploma
Mechanical Engineering
21 Heavy mining equipment
North Heap Leach facility
Gold Fields LimitedTarkwa Gold Mine
Plan showing mine infrastructure as at 31 December 2012
Page w
idth 208 mm
Page w
idth 205 mm
12. Brief history
The history of Tarkwa
Late 1800s: Several small mining companies operated the Abontiakoon concession.
1935: Amalgamated Banket Area Limited (ABA) acquired the Abontiakoon concession. Sinking of the
Abontiakoon vertical shaft.
1936 – 1940: Construction of new central mill with a capacity of 30 ktpm.
1960: All workings abandoned and allowed to flood.
1961: Production restarted under the State Gold Mining Corporation.
1963: The Tarkwa mines renamed Tarkwa Goldfields Limited.
1973 – 1976: Apinto Shaft sunk to access additional ore sources.
1993: GFGL signed a management contract with the Ghanaian government to operate the mine.
1996: Feasibility study completed by GFGL on an open pit/heap leach operation.
1998: Initial Tarkwa Phase I development completed for an open pit operation mining 14.5 Mtpa including
4.7 Mtpa of heap leach feed ore.
1999: Tarkwa Phase II expansion completed to increase mining rate to 20.7 Mtpa and with heap leach ore
production to 7.2 Mtpa. All underground operations and associated processing plant ceased production.
2000: GFGL acquired northern area of Teberebie. Mining production pushed to 36 Mtpa.
2004: Tarkwa implemented owner mining in July 2004 and commissioned a CIL plant with a nameplate capacity
of 4.2 Mtpa in October 2004.
2008: South Heap Leach facility ceases crushing in December 2008.
2009: Expanded CIL plant commissioned in January 2009, design throughput of 12.3 Mtpa achieved in
September 2009. HPGR 1 Mt plant scale test conducted at South Heap Leach facility in last quarter of
the year.
2010: Conversion to owner maintenance implemented with the inherent cost savings and productivity gains
expected to materialise in 2011.
2011: Gold Fields Ghana Limited acquired the 18.9% IAMGold interest in Tarkwa and now holds 90% with the
remaining 10% held by the Ghanaian government.
2012: CIL Secondary crushing plant commissioned and South Heap Leach stopped.
Photographs showing the recently installed water purification system
17 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
Akontansi Cut 7 looking East, Tarkwa
Tarkwa 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’)
345.2 Mt @ 1.3 g/t14.6 Moz
293.3 Mt @ 1.07 g/t10.1 Moz
185.3 Mt @ 0.95g/t5.7 Moz
108.0 Mt @ 1.27 g/t4.4 Moz
30.1 Mt @ 2.92 g/t2.8 Moz
198.0 Mt @ 1.00 g/t6.3 Moz
117.1 Mt @ 1.43 g/t5.4 Moz
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
18 � Gold Fields – Tarkwa Gold Mine – Technical Short Form Report 2012
This Technical Short Form Report (the Report) contains information as at 31 December 2012 (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 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.
Notes
BASTION GRAPHICS
Open pit mining operations
Registered Office South Africa:
150 Helen RoadSandownSandton, 2196JohannesburgGauteng
Private Bag X30500Houghton, 2041South Africa
Website: http://www.goldfields.co.zaTelephone: +27 (0) 11 562 9700Facsimile: +27 (0) 11 562 9838
“If we cannot mine safely, we will not mine”
Gold Fields Safety Value
Recommended