|
|
| Tarkwa Gold Mine
Technical Short Form Report
This Technical Short Form Report reflects the latest Life of Mine plan, coupled with an
updated Mineral Resource and Mineral Reserve statement, as at 30 June 2009.
Gold 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
71.1% of the issued shares of GFGL. IAMGold, through its affiliates, holds 18.9% and the
Government of Ghana holds a 10% free carried interest, as required under the Mining Law
of Ghana.
Tarkwa is located near the southern end of what is commonly referred to as The Tarkwa
Basin, 300 km by road west of Accra, the capital of Ghana. The Tarkwa mine operates under
mining leases covering a total area of approximately 20,800 ha. In F2009 Tarkwa produced
0.612 Moz of gold from heap leach and milling operations at a cash cost of US$521/oz.
Tarkwa employed a workforce of 3,982 as of 30 June 2009, including contractors.
The geological and evaluation models have been updated to reflect the latest available data
sets. These models are coupled with an integrated and holistic mine design and schedule
plan that is based on current performance levels and takes cognisance of the inherent risks
associated with mining operations at Tarkwa Gold Mine.
All Mineral Resource and Mineral Reserve figures reported are managed unless otherwise
stated and Mineral Resources are inclusive of Mineral Reserves.
Salient Features
- The Carbon in Leach (CIL) plant expansion project was successfully
commissioned in January 2009 and as a result increased the capacity to
12.3 Mpta.
- Solid anchor for growth in the West Africa Region.
- Mineral Resource of 16.2 Moz.
- Mineral Reserve of 10.7 Moz.
- A pilot plant for testing High Pressure Grinding Rolls (HPGR) is being
installed and is planned to be completed in F2010.
- Life of Mine extends to 2022 (13 years).
Mining activities around Tarkwa date back to the late 19th century. Gold Fields Ghana operated
the underground mine which exploited the Main and West auriferous conglomerates (reefs) of
the Banket Series of the Tarkwaian System. These reefs were mined from two vertical shafts,
(Abontiakoon and Apinto), from 1993 until 1999.
In 1996 a pre-feasibility study, followed by a positive feasibility, led to the approval for the
development of an open pit Heap Leach operation to the northwest of the underground workings
to exploit the outcropping and near surface multiple conglomerate horizons of the Banket Series.
In 1998 the initial development was completed on Tarkwa Phase I, the 14.5 Mtpa open-pit mining
operation supplying 4.7 Mtpa of ore to the North Heap Leach Facility. From 1999 to 2008 the
Tarkwa operation expanded through another three phases, which included the acquisition of
Teberebie from Ghanaian Australian Goldfields Limited and the re-commissioning of the Teberebie
open pit and heap leach pads to the current expanded capacity of the CIL plant. |
Key Features
| |
Independent Audit |
|
Figures reported in this declaration are as reviewed and approved by independent external consultants as at 30 June 2009 |
| |
Prepared by |
|
Gold Fields Limited |
| |
Effective date |
|
30 June 2009 |
| |
Source of Information |
|
This Technical Statement is a summary of the internally sourced document entitled F2010 Tarkwa Competent
Persons Report |
| |
Personal Inspection |
|
Personal inspection is conducted by the Competent Persons as listed, who are full time employees of Gold Fields
Limited |
| |
General Location |
|
Tarkwa is located in south-western Ghana approximately 300 km by road west of Accra, the capital, at a latitude
5° 15’ N and longitude 2° 00’ W. The Tarkwa mine is located 4 km 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 km to the southeast on the Atlantic coast |
| |
Licence Status and Holdings |
|
The Tarkwa mine operates under mining leases covering a total area of approximately 20,800 ha. Five mining
leases cover the Tarkwa concession each dated April 18, 1997 in respect of operations at the Tarkwa property,
and two mining leases dated 2 February 1988 and 18 June 1992 respectively, for the operations at the Teberebie
property. The Tarkwa concession mining leases expire in 2027 and the Teberebie property mining leases expire
in 2018 |
| |
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 2008 utilised a conventional Carbon-in-Leach (CIL) plant
as well as a Heap Leach facility |
| |
Climate |
|
Although there may be minor disruptions to operations during the wet session, there are no long term constraints
on production due to climate |
| |
Deposit Type |
|
The open-pit surface operation currently exploits narrow, tabular auriferous conglomerates from six open pits,
Pepe, Atuabo, Mantraim, Teberebie, Akontansi and Kottraverchy |
| |
Life of Mine (LoM) |
|
It is estimated that the current Mineral Reserve will be depleted in 2022 |
| |
Environmental |
|
Tarkwa retained its ISO 14001:2004 Environmental Management System and certification following an external
audit during the year. The mine also retained its full compliance to the ICMI Cyanide Management code |
| |
Regulatory 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 a sufficient Mineral Resource Management process and protocol to
ensure adequate corporate governance in respect of the intent of the Sarbanes-Oxley Act |
| Gold Fields has
stated that: “If we cannot mine
safely, we will not
mine”. This principle
is embedded at
Tarkwa. |
Operating Statistics
| |
Total tons mined |
’000 tons |
|
132,585 |
|
113,341 |
|
107,582 |
|
96,936 |
|
82,471 |
|
| |
Stripping ratio |
Ore: waste |
|
5.1 |
|
4.7 |
|
4.0 |
|
3.6 |
|
3.3 |
|
| |
Tons processed Heap Leach |
’000 tons |
|
13,540 |
|
16,464 |
|
17,019 |
|
16,800 |
|
16,444 |
|
| |
Tons processed CIL |
’000 tons |
|
7,733 |
|
5,571 |
|
5,620 |
|
4,687 |
|
3,189 |
|
| |
Source of ore |
|
|
|
|
|
|
|
|
|
|
|
|
| |
– Underground |
’000 tons |
|
– |
|
– |
|
– |
|
– |
|
– |
|
| |
– Head grade |
g/t |
|
– |
|
– |
|
– |
|
– |
|
– |
|
| |
– Surface |
’000 tons |
|
21,273 |
|
22,035 |
|
22,639 |
|
21,487 |
|
19,633 |
|
| |
– Head grade heap leach |
g/t |
|
0.9 |
|
1.0 |
|
1.1 |
|
1.2 |
|
1.3 |
|
| |
– Head grade CIL |
g/t |
|
1.4 |
|
1.5 |
|
1.5 |
|
1.6 |
|
1.5 |
|
| |
– Head grade total |
g/t |
|
1.1 |
|
1.2 |
|
1.2 |
|
1.3 |
|
1.3 |
|
| |
Average yield total |
g/t |
|
0.9 |
|
0.9 |
|
1.0 |
|
1.0 |
|
1.1 |
|
| |
Gold produced |
kg |
|
19,048 |
|
20,095 |
|
21,684 |
|
22,060 |
|
21,051 |
|
| |
Gold produced |
’000 oz |
|
612 |
|
646 |
|
697 |
|
709 |
|
677 |
|
| |
Operating cost |
|
|
|
|
|
|
|
|
|
|
|
|
| |
– Surface |
US$/oz |
|
523 |
|
431 |
|
357 |
|
298 |
|
236 |
|
| |
– Surface |
US$/ton |
|
15.9 |
|
12.6 |
|
11.0 |
|
9.6 |
|
8.1 |
|
| |
– Cash cost |
US$/oz |
|
521 |
|
430 |
|
333 |
|
292 |
|
234 |
|
| |
– Cash cost |
US$/ton |
|
15.0 |
|
12.6 |
|
10.2 |
|
9.6 |
|
8.1 |
|
| |
Capital expenditure |
US$ (million) |
|
201 |
|
212 |
|
108 |
|
48 |
|
76 |
|
| |
NCE |
US$/oz |
|
881 |
|
766 |
|
512 |
|
– |
|
– |
|
| |
Number of employees |
TEC’s |
|
3,982 |
|
3,565 |
|
3,247 |
|
3,068 |
|
2,830 |
|
| |
Declaration Date |
|
|
30 Jun 09 |
|
30 Jun 08 |
|
31 Dec 06 |
|
31 Dec 05 |
|
30 Jun 05 |
|
| |
Expected Life-of-Mine |
years |
|
13 |
|
14 |
|
15 |
|
22 |
|
20 |
|
| |
Mineral Reserves |
Mt |
|
270 |
|
285 |
|
312 |
|
353 |
|
324 |
|
| |
Head Grade of Mineral Reserves |
g/t |
|
1.2 |
|
1.2 |
|
1.3 |
|
1.3 |
|
1.3 |
|
Rounding off of figures presented in this report may result in minor computational discrepancies.Where this occurs it
is not deemed significant.
Geological Setting and
Mineralisation
The Tarkwa ore bodies are located within the
Tarkwaian System, which forms a significant
portion of the stratigraphy of the AshantiBelt in
southwest Ghana. The AshantiBelt is a northeasterly
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,
which from oldest to youngest are:
- Kawere Series (250 – 700 m) – poorly sorted,
polymictic conglomerates and quartzites
with no significant mineralisation;
- Banket Series – well sorted conglomerates
and quartzites with clasts generally
considered to be Birimian in origin and
containing significant gold mineralisation,
hosting the Tarkwa ore body. In the Pepe
area the Banket Series is approximately
32 m thick and at Kottraverchy up to
270 m thick;
- Tarkwa Phyllite Series (120 – 140 m) – fine
grained chloritic siltstones, mudstones and
schists with no significant mineralisation;
and
- Huni Series (1,370 m) – fine grained
massive meta-arenites with no significant
mineralisation.
 |
| Surface geology and infrastructure |
 |
| Teberebie G reef |
Local geology
The local geology at Tarkwa is dominated
by the Banket Series, which can be further
sub-divided into a footwall and hanging wall
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 inter-bedded with barren immature
quartzites. The units thicken to the west and
current flow parameters indicate a flow from the
east and northeast. Structurally, the Tarkwaian
belt has been 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 development
of thrust faults and reversing of previous
normal faults. The final stages involved further
thrusting in a southwest direction.
The mineralised and potentially economic
conglomerate reefs are identified below from
the base upwards (younging):
- AFc – 0.2 – 3.0 m thick, only occurs in the
west and subcrops against the A1 in the
east. Well sorted with rounded clasts of
quartzite and visible gold;
- A1 – between 2 – 7 m thick, moderately
to poorly sorted conglomerate and thin
quartzites with occasional visible gold;
- A3 – occurs up to 7 m thick, moderately
sorted, the conglomerate forms as thin
discontinuous lenses within a package of
cross bedded quartzites, visible gold is
rare;
- B2 (or B) – up to 3 m thick, very coarse
quartzites with thin lags of sub-rounded
pebble conglomerate does not occur
in the Akontansi ridge or Kottraverchy
areas;
- CDE – up to 8 m 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 2 m thick, essentially a
marker horizon, except in the east where
it carries low grades; and
- G – varies from a 2 – 6 m thick poorly
sorted conglomerate with clasts of
quartzite and phyllite.
Sedimentological studies of the detailed
stratigraphy within individual 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 (basin
down warp time units T1 and T2), through a
period of uplift and reworking (T3). Finally, a
period of meandering channel bars and flow
reduction led to the development of low grade
conglomerates with silty interbeds (T4). This
sequence has been recognised in each of the
main reef units with the T3 sequence being
the principal episode of gold deposition and
concentration.
 |
| Schematic sedimentological profile through the Tarkwa orebody |
Exploration and drilling
The bulk of the Tarkwa open pit palaeoplacer
Resource has been drilled to Measured and
Indicated categories at current costs and
a gold price of US$1,000/oz. A Regional
prospectivity study conducted in 2004, did not
reveal any further palaeoplacer nor significant
hydrothermal gold targets on the Tarkwa lease
area. One minor hydrothermal target identified
in the study has been previously drilled and
no hydrothermal gold mineralisation was
intersected. Tarkwa is now a mature mine
and the focus has shifted from exploration to
optimising the extraction of the current Mineral
Resource.
Future diamond drilling programs will be
guided by the “unconstrained” Whittle® pit
optimisations which may indicate the potential
for economically viable extraction of pay shoots
down-dip of current pits. Infill diamond drilling
programmes will also be considered where
there is the need to increase resource definition
to upgrade the Mineral Resource category
ahead of mining and to provide detailed
information for assessment of alternative select
mining cuts of the reef packages.
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. The mine
operates its own load and haul fleet of
14 excavators, ranging from 120 to 295
tons, 44 dump trucks with a payload of
144 tons as well as ancillary equipment.
24 Owner operated drill rigs are used for blast
hole drilling. Equipment maintenance is carried
out by MARC contractors. In F2010 Tarkwa
plans to mine a total of 145.8 Mt of material at
a stripping ratio of 5.7 to 1.
Mining methods
The mining methodology used is highly
selective. 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 with a bulldozer.
The topsoil is relocated for rehabilitation
purposes. After clearing, reverse circulation
grade control drilling is carried out, and
geological models constructed. The short-term
plans and forecasts are updated with
this grade control information prior to the
commencement of mining. From the highest
point in the pit, material is free-dug or blasted
to the first blasting reference level. Currently
fresh rock and transitional zones are drilled
and blasted in 6 m lifts, with excavation in
3 m flitches. Fourteen backhoe excavators are
used to select waste from the ore, and vice
versa, along the sedimentary horizons to an
average accuracy of 30 cm on the hanging
wall and 20 cm on the footwall of a reef.
Pit Geologists and Geotechnicians supervise
all digging and mineral material is classified as
either RoM, 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 m by 3.8 m grid with a hole diameter of
118 mm 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, whilst 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.
Truck allocation (dispatching) is by means of
the LP-based, GPS assisted Modular Mining
Fleet Management System. Management
reporting of material movement is via an
intranet-based system (MMRS) which “reads”
the data off the Modular Database in which all
relevant information is stored.
 |
| Mining slope with geological staff supervising the select mining activities of a 295 ton excavator |
Mine planning and scheduling
In general, all mine design and scheduling
is undertaken using Surpac®, Datamine®,
Whittle®, Xeras® , Xpac® and in-house
computer software. The planning cycle
commences with the ratification of key input
parameters, prior to producing a compliant
Mineral Resource statement adjusted for all
Mineral Resource depletions.
On completion of the Mineral Resource
update, the planning process commences,
incorporating a Corporate decision on macro
economic parameters, development of a two-year
operational plan (top down goals, which
are derived from the previous year’s strategic
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.
 |
| Kottraverchy block model and LoM pit design |
A cut–off grade strategy is used in the Mineral
Reserve estimation process. The process
cut-off defines the ore/waste segregation,
and a cut-over grade defines mill/heap
leach segregation. A third cut-off, termed
the optimal cut-off/cut-over, is also derived,
which can be applied to increase the grade
and therefore 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.
For all operational plans, a detailed (two-year)
operating and capital cost budget is produced
and where appropriate extended for the LoM
production schedule.
Zero-based costing is used to formulate the
two-year plan. Historically achieved data for
productivity and operating costs, is 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.
Projects
The South Heap Leach facility ceased
crushing in December 2008 to coincide with
the commissioning of the expanded CIL plant.
The decreased availability of high dissolution
(high recovery) ore that is amenable to heap
leaching necessitated the reduced heap leach
and expanded CIL milling capacity.
A 500 t/h High Pressure Grinding Roller (HPGR)
unit is being added onto the crushing circuit at
the South facility in order to conduct a plant
scale test of the HPGR technology. The HPGR
unit will crush 1 Mt of low dissolution material
during F2010 with the aim of determining
improved gold recovery, heap stability at
the finer crush and reliabilty of the HPGR
equipment. Positive results from this test will be
considered for application at the North Heap
Leach facility.
Scoping studies have been carried out to
assess the viability of relocating the South
Facility primary crusher closer to Teberebie
or Akontansi pit with the aim of using in-pit
crushing and conveying to reduce mining
costs. The scoping studies have indicated
that the most attractive option is to relocate
the crusher to Teberebie pit for ore crushing.
This will reduce mining costs and provide
a risk mitigating alternative to the primary
crusher currently feeding the CIL plant.
This project will be taken to pre-feasibility level
in the future.
Three other projects that have been initiated
and will be accelerated during F2010:
- optimising the LoM waste stripping
schedule;
- optimising the LoM waste dumping
schedule; and
- improving the LoM water control plan.
Each of these initiatives is aimed at improving
profitability of the Mineral Reserve.
Mineral Processing
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.
The ore is a free milling conglomerate with
negligible sulphide content. Weathering
has affected rocks near the surface and a
higher degree of weathering is associated
with increased porosity and increased
Heap Leach dissolution and recovery.
The North Heap Leach was commissioned
in 1998 to process the initial high porus
ore. Phase V Heap Leach pad construction
was completed in 2009 and a further three
phases of Heap Leach pad construction
have been accounted for in the LoM plan. 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 that was 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 employs three
stages of crushing prior to agglomeration.
Agglomeration involves the addition of 4 kg/t
of cement to the crushed rock to bind the
fine material and produce an 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 where the gold is adsorped onto
activated carbon, removed from the carbon
by acid wash, and recovered using electro
winning. The North facility has a smelt house
with diesel fired furnaces to smelt all gold
produced at the North facility.
The CIL process route has a 54” x 75”
Gyratory crusher that feed two crushed
ore stockpiles that have a live capacity of
45,000 t (30 hours). Underneath each stockpile
is a reclaim tunnel, with apron feeders
that feed onto a conveyor belt, which in
turn feeds the milling circuit. The milling circuit consists of a SAG and Ball mill with
recycle crushing in closed circuit with the
SAG mill. The SAG Mill has an Effective
Grinding Length of 42’ with an internal
diameter of 27’ and 14 MW of installed
power (2 x 7,000 kW twin drive motors).
The ball mill has an effective grinding length
of 36’ with an internal diameter of 26’ and
14 MW of installed power (2 x 7,000 kW
twin drive motors). The milling circuit is
operated at a capacity of 1,490 tph. The
CIL circuit consists of two trains of eight
tanks in series fed from a common leach
tank. The loaded carbon passes into a
15 t acid wash column. The gold is recovered
from the loaded carbon in two 15 t elution
circuits. Gold is recovered from solution by
electrowinning. The gold is smelted in the
CIL smelt house in an induction furnace.
 |
| CIL plant SAG mill |
Sustainable Development
Tarkwa manages risk to control and where
possible, eliminate hazards in the working
environment. Tarkwa strives to achieve and
maintain an outstanding health and safety
performance through the participation of
all employees and the application of safe,
innovative processes and technologies,
within a framework of OHSAS 18001 and full
compliance. A comprehensive external audit
of Tarkwa’s Full Compliance Health and Safety
Management System has been undertaken
annually since 2005 and certification retained
to date.
The OHSAS 18001 system is in alignment with
Gold Fields Limited “Full Compliance Health
and Safety Management System”, which is the
Group-wide standard for the management of
occupational health and safety in Gold Fields.
This aims to achieve:
- the elimination of all fatal accidents at all
Gold Fields operations;
- a 50 per cent reduction in all accident rates
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 in comprising Informed Consent
Voluntary Counselling and Testing (ICVCT),
disease prevention and health promotion
programmes. Tarkwa appointed a HIV/AIDS
Co-ordinator, who drives and oversees the
implementation of a HIV/AIDS programme
with the full co-operation of the Employee
Representative bodies and according to
International Labour Organisation and Gold
Fields Group standards. The Co-ordinator
has incorporated HIV/AIDS into the induction programme on the mine for both employees
and contractors. Peer educators facilitate
discussions on HIV/AIDS during Health and
Safety Meetings as well as providing formal
counselling and training to both on-site and-off
site communities.
Cyanide is managed under the framework of
the International Cyanide Management Code.
Tarkwa gold Mine was certified as ICMC
compliant in June 2008. Under the Cyanide
code, all suppliers and transporters of cyanide
to the mine must comply with the code to
ensure the safe use of cyanide. Strict use of
cyanide on site is continually monitored and
necessary changes are incorporated into
operational procedures.
Environmental management at Tarkwa
is conducted within the framework of an
ISO14001:2004 certified Environmental
Management System. Tarkwa operations
are operated in accordance with Ghanaian
environmental requirements, as administered
by the EPA, and hold the required Environmental
Permits and valid Environmental Certificates.
Tarkwa complies with the EPA requirements to
provide monthly monitoring returns, an annual
environmental report and an update of the
EMP at intervals of three years. An EIS for the
Tarkwa Expansion Project was submitted to
the Ghana EPA in March 2007. The document
was approved on 27 May 2007.
An updated EMP was submitted to the EPA
on 22 November 2008 as required under
the legislation. A costed reclamation and
decommissioning plan (CRDP) for Tarkwa
was completed in 2001 and updated in March
2004. A subsequent update was submitted
in June 2006. A revised CRDP covering the
period to December 2008 is currently being
finalized on site for submission to the EPA
during July 2009.
| F2009 |
|
| |
Fatalities |
(No) |
1 |
|
1 |
|
0 |
|
3 |
|
0 |
|
| |
Fatality Rate |
(per mmhrs) |
0.1 |
|
0.1 |
|
0 |
|
0.2 |
|
0 |
|
| |
LDIFR |
(per mmhrs) |
0.7 |
|
0.6 |
|
0.2 |
|
0.3 |
|
0.3 |
|
 |
| Expanded CIL plant – SAG mill (left) and Ball mill (right) |
Mineral Resource and Mineral Reserve
Unless otherwise stated all Mineral Resources and Mineral Reserves are quoted as 100% and are not attributable with respect to ownership.
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 five percent for processing purposes
as experience has show that this is realistically achievable when reclaiming a stockpile. RoM stockpile tonnages were reconciled to survey volumes
in June 2009.
Mineral Resources
Mineral 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 required to be mined to extract the complete pay portion of the Mineral Resource.
| June 09 |
|
June 09 |
|
June 09 |
|
| |
Open pit and underground |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
Measured |
144.7 |
|
149.0 |
|
144.1 |
|
1.5 |
|
1.4 |
|
1.5 |
|
6,800 |
|
6,914 |
|
6,790 |
|
| |
Indicated |
173.4 |
|
146.1 |
|
191.0 |
|
1.2 |
|
1.3 |
|
1.3 |
|
6,705 |
|
6,021 |
|
8,122 |
|
| |
Inferred* |
26.0 |
|
24.4 |
|
51.1 |
|
3.1 |
|
3.1 |
|
2.4 |
|
2,569 |
|
2,411 |
|
3,879 |
|
| |
Total open pit and underground |
344.1 |
|
319.5 |
|
386.2 |
|
1.5 |
|
1.5 |
|
1.5 |
|
16,075 |
|
15,346 |
|
18,792 |
|
| |
Surface |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
Measured stockpiles |
4.7 |
|
3.9 |
|
6.2 |
|
0.8 |
|
0.7 |
|
0.8 |
|
112 |
|
90 |
|
154 |
|
| |
Total surface stockpiles |
4.7 |
|
3.9 |
|
6.2 |
|
0.8 |
|
0.7 |
|
0.8 |
|
112 |
|
90 |
|
154 |
|
| |
Grand Total |
348.7 |
|
323.4 |
|
392.4 |
|
1.4 |
|
1.5 |
|
1.5 |
|
16,187 |
|
15,435 |
|
18,945 |
|
*F2010 includes underground Mineral Resources of 21.2 Mt @ 3.53 g/t
Modifying factors
- The Measured and Indicated Mineral
Resource are inclusive of those Mineral
Resources modified to produce Mineral
Reserves;
- All Mineral Reserves are quoted in terms of
Run-of-Mine (RoM) grades and tonnages
as delivered to the metallurgical processing
facilities and are therefore fully diluted; and
- Mineral Resources and Mineral Reserves
undergo both internal and external audits
either during the year, yearly or bi-annually,
and any issues identified are rectified at
the earliest opportunity, during the current
reporting cycle.
 |
| North Heap Leach phase V expansion |
| |
Mineral Resource Gold Price |
US$/oz |
1,000 |
|
| |
Cut off for heap leach |
g/t |
0.24 |
|
| |
Cut off for mill feed |
g/t |
0.35 |
|
| |
Cut off for underground |
g/t |
2.46 –3.08 |
|
| |
Mineral Reserve Gold Price |
US$/oz |
800 |
|
| |
Cut off for heap leach |
g/t |
0.30 |
|
| |
Cut off for mill feed open pit |
g/t |
0.43 |
|
| |
Stripping ratio |
waste:ore |
4.6 |
|
| |
Dulution (open pits) |
% |
11 |
|
| |
Plant recovery factor fresh ore |
% |
97 |
|
| |
Plant recovery factor oxide ore |
% |
97 |
|
| |
Heap Leach recovery factor |
% |
64 |
|
| |
Processing capacity |
Mtpa |
12.3 |
|
| |
Heap Leach capacity |
Mtpa |
9.8 |
|
Grade tonnage curves
The open pit grade tonnage curve represents
undiluted grade and tons within the diluted
optimised shell. Underground Mineral
Resources are inclusive of dilution.
Open pits

Underground

Mineral Reserves
The 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 appropriate level of detail by experienced engineers using appropriate mine planning software.
The planning process incorporates appropriate modifying factors and the use of cut-off grades and other technical-economic investigations.
Mineral Reserve statements include only Measured and Indicated Mineral Resources modified to produce Mineral Reserves, and contained in the
LoM plan.
| June 09 |
|
June 09 |
|
June 09 |
|
| |
Open pit |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
Proved |
149.6 |
|
155.0 |
|
153.6 |
|
1.3 |
|
1.3 |
|
1.3 |
|
6,220 |
|
6,371 |
|
6,468 |
|
| |
Probable |
116.0 |
|
126.6 |
|
152.1 |
|
1.2 |
|
1.2 |
|
1.2 |
|
4,354 |
|
4,857 |
|
6,054 |
|
| |
Total open pit |
265.6 |
|
281.6 |
|
305.7 |
|
1.2 |
|
1.2 |
|
1.3 |
|
10,575 |
|
11,228 |
|
12,521 |
|
| |
Surface |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
Probable stockpiles |
4.4 |
|
3.7 |
|
5.9 |
|
0.7 |
|
0.7 |
|
0.7 |
|
101 |
|
85 |
|
141 |
|
| |
Total surface stockpiles |
4.4 |
|
3.7 |
|
5.9 |
|
0.7 |
|
0.7 |
|
0.7 |
|
101 |
|
85 |
|
141 |
|
| |
Grand Total |
270.0 |
|
285.3 |
|
311.7 |
|
1.2 |
|
1.2 |
|
1.3 |
|
10,676 |
|
11,313 |
|
12,662 |
|
Mineral Reserves by mining area
| |
Akontansi |
56.8 |
|
1.23 |
|
2,237 |
|
88.5 |
|
1.12 |
|
3,202 |
|
| |
Kottraverchy |
8.4 |
|
1.46 |
|
393 |
|
– |
|
– |
|
– |
|
| |
Pepe / Mantraim |
33.1 |
|
1.20 |
|
1,275 |
|
6.2 |
|
1.09 |
|
217 |
|
| |
Teberebie |
51.3 |
|
1.40 |
|
2,315 |
|
21.2 |
|
1.37 |
|
935 |
|
| |
Surface stockpile |
4.4 |
|
0.71 |
|
101 |
|
– |
|
– |
|
– |
|
| |
Grand Total |
154.0 |
|
1.27 |
|
6,322 |
|
116.0 |
|
1.17 |
|
4,354 |
|
Mineral Resources and Mineral Reserves Reconciliation year-on-year
Mineral Resource
Factors that affected Mineral Resource reconciliation:
- Depletion by mining (RoM and low grade ore);
- Increased cost; and
- Increase in gold price outstripped depletion and cost imputs
and accounts for the bulk of the increase of Mineral Resource.
Change in Mineral Resource F2009 to F2010

Mineral Reserve
Factors that affected Mineral Reserve reconciliation:
- Decrease was mainly due to increase in cost, which eroded gains
due to increase in gold price;
- Depletion by mining and includes both RoM and low grade; and
- Engineering design loss.
Change in Mineral Reserve F2009 to F2010

Mineral Reserve sensitivity
The Mineral Reserve sensitivity has been
derived from the application of the relevant cutoff
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, +5%, +10% and +25% to the gold price.
Managed Mineral Reserve Sensitivity

Mineral Reserve split by source between CIL plant and Heap Leach
| June 2009 |
|
June 2009 |
|
June 2009 |
|
| |
Open Pit |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
CIL Plant |
153.8 |
|
160.6 |
|
159.9 |
|
1.5 |
|
1.5 |
|
1.5 |
|
7,356 |
|
7,670 |
|
7,866 |
|
| |
Heap Leach |
111.8 |
|
121.0 |
|
145.8 |
|
0.9 |
|
0.9 |
|
1.0 |
|
3,219 |
|
3,558 |
|
4,655 |
|
| |
Total Open Pit |
265.6 |
|
281.6 |
|
305.7 |
|
1.2 |
|
1.2 |
|
1.3 |
|
10,575 |
|
11,228 |
|
12,521 |
|
| |
Stockpiles |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
CIL Plant |
1.7 |
|
0.8 |
|
– |
|
0.7 |
|
0.6 |
|
– |
|
38 |
|
15 |
|
– |
|
| |
Heap Leach |
2.7 |
|
3.0 |
|
5.9 |
|
0.7 |
|
0.7 |
|
0.7 |
|
63 |
|
70 |
|
141 |
|
| |
Total Stockpiles |
4.4 |
|
3.7 |
|
5.9 |
|
0.7 |
|
0.7 |
|
0.7 |
|
101 |
|
85 |
|
141 |
|
| |
Grand Total |
270.0 |
|
285.3 |
|
311.7 |
|
1.4 |
|
1.2 |
|
1.3 |
|
10,676 |
|
11,313 |
|
12,662 |
|
Regulatory Codes
SAMREC
This 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).
JSE
This Technical Statement has been prepared in compliance with the listing requirements of the JSE Securities Exchange, South Africa (JSE), specifically Section 12 – Issue 11.
Sarbanes-Oxley Act
The Mineral Resource and Mineral Reserve is underpinned by an adequate Mineral Resource Management process and protocol to ensure adequate corporate governance in respect of the intent of the Sarbanes-Oxley Act.
Environmental
Tarkwa has an environmental management team who are supported by specialist assistance from the Corporate office in Johannesburg. The systems, procedures, training etc. are at international best practice levels. Gold Fields has produced a Sustainability Report in 2009 and intends reporting annually in accordance with the Global Reporting Initiative.
Competent Persons
Mr C. Duvel: Mineral Resource Manager
BSc (Hons.) (Geology), GDE (Mining Engineering), (SACNASP; Registration number 400007/98). Mr C. Duvel has over 14 years experience in the
mining industry and is responsible for the overall correctness, standard and compliance of this declaration. He is a competent person in placer and
hydrothermal gold mineralization
Mr G.S.G. Chapman: Operations Manager
BSc (Hons.) (Geology) (SACNASP; Registration number 400694/83). Mr G.S.G. Chapman has over 33 years experience in the mining industry and is responsible for the review of the mine planning and financial analysis of this declaration.
Key Technical Staff
| |
Post |
Incumbent |
|
Qualification |
Years |
Key Responsibility |
|
| |
General Manager |
P.J. van Schalkwyk |
|
BSc (GeoChem), CPIR |
25 |
Responsible for overall
strategic direction,
leadership and
management |
|
| |
Operations Manager |
G.S.G. Chapman |
|
BSc (Hons.) (Geology), Pr. Sci. Nat.
(SACNASP; Registration no. 400694/83) |
33 |
Site operations,
including mining, mining
maintenance, engineering
operations, process and
Mineral Resources |
|
| |
Manager Mining |
P. von Kpekpena |
|
BSc (Mining), GDE Mining, Mine
Managers Certificate (SA, Tanzania,
Ghana), MDP (GIBS, SA) |
18 |
Full operational
management |
|
| |
Acting Financial Manager |
E. Asubonteng |
|
BSc Administration, Association of
Chartered Certified Accountants (ACCA) |
8 |
Financial reporting and
compliance |
|
| |
Human Resources
Manager |
M. van der Merwe |
|
IPM Diploma (M+3) |
23 |
Human resource
management |
|
| |
Metallurgy Manager HL |
J. Huffman |
|
BSc (Mineral Processing and Extractive
Metallurgy) |
34 |
Mineral Processing &
Metallurgy Heap Leach |
|
| |
Metallurgy Manager CIL |
M. Lombaard |
|
B Eng. Metallurgical Engineering |
11 |
Mineral Processing &
Metallurgy CIL |
|
| |
Engineering Manager –
Process |
H. de Beer |
|
Diploma Mechanical Engineering
Government Certificate of Competency |
28 |
Process Engineering,
logistics and infrastructure
management |
|
| |
Safety Manager |
D. Pienaar |
|
NADSAM (M+3) |
20 |
Health & Safety |
|
| |
Environmental Manager |
T. Morris |
|
BSc, Dip EIA |
29 |
Environmental management |
|
| |
Mineral Resources
Manager: Mine Planning and
Resource Management |
C.Duvel |
|
BSc (Hons.) (Geology), GDE (Mining
Engineering), Pr. Sci. Nat. (SACNASP;
Registration no. 400007/98) |
14 |
Mine Planning, Mineral
Resources & Mineral
Reserves and compilation
of CPR |
|
| |
Manager Community &
Public Affairs |
Dr. S. Yirenkyi |
|
BA (Development Planning) (KNUST) |
13(GFG) |
Community and public
affairs |
|

Tarkwa History
at a Glance
|