AngloGold Ashanti, one of the world’s
largest gold mining have operation mines in nine countries across
Africa, South America, and Australia. With significant scale but high
all-in sustaining costs, or AISC, AngloGold was geared to generate
significant free cash flow during gold’s bull run that ended in 2013.
Since the fall in gold prices, management has focused on cutting its
AISC.
Roughly a third of AngloGold’s production
is based in South Africa. These underground mines are some of the
deepest in the world, and operating costs and safety risks continue to
escalate. Furthermore, high labor costs stemming from a unionized
workforce historically unafraid to strike and high electricity costs
push costs in the region even higher.
Another third of production is based in
Central Africa. These mines have high costs and face added risk from
political instability. For example, the company’s Kibali joint venture,
expected to provide growth at costs below the company average, is in the
Democratic Republic of Congo, which has appropriated foreign mining
assets in the past. The remaining third of production is in Australia
and the Americas, where the mines exhibit lower costs than their African
counterparts and have lower geopolitical risk.
AngloGold Ashanti’s five South African
deep-level mines and surface production facilities are divided into
three areas of operation: Vaal River, West Wits and Surface Operations.
At present, these three areas comprise the following operations:
This is mining operations AngloGold Ashanti in Region South Africa
Vaal River
The Vaal River mining operations comprise
three mines located around 170km to 180km from Johannesburg, near the
Vaal River on the Free State-North West Province border. These three
mines, which share a milling and treatment circuit, are:
- Great Noligwa Mine
Great Noligwa, a mature operation
nearing the end of its life, adjoins Kopanang and Moab Khotsong in the
Free State. The mine primarily exploits the Vaal Reef by means of
scattered mining via a twin-shaft system over three main levels at an
average depth of 2,100m. Great Noligwa has its own dedicated milling and
treatment plant which applies conventional crushing, screening,
semi-autogenous grinding and carbon-in-leach processes to treat the ore
and extract the gold. The plant has a nominal throughput capacity of
230,000 tpm
The reefs mined at Great Noligwa are the
Vaal Reef and the Crystalkop Reef, with the Vaal Reef accounting for
over 90% of the gold produced in the mine. The Vaal Reef consists of 85%
of the ore reserve tonnage with mining grades between 10g/t and 20g/t.
In 2008, the Vaal River operations (including surface operations)
produced 34,785kg (1,119,000oz) of gold, equivalent to 22% of group
production.Production at Great Noligwa fell significantly in 2008
because of a transfer of the SV4 section to Moab Khotsong from where it
is more easily accessible.
The complexity of the ore at Great
Noligwa has necessitated a scattered mining strategy comprising a
twin-shaft system serving eight main levels at an average depth of
2,400m.The reef is accessed from the footwall haulage and return airway
development, with cross-cuts spaced every 180m to the reef
horizon.Raises are then developed on-reef to the level above and the
reef is stoped out on strike with an average stope width of 150cm.
Approximately 4,000m of development is completed each quarter.The
orebody is narrow and tabular and averages 35,000m² a month. Panels are
on average 26m long.
As the operation ages, mining methods are
converting from conventional scattered mining to pillar or remnant
mining. Until now the Vaal Reef has been the most economically viable
reef to mine. However, as this reef is mined out, the less economical
Crystalkop Reef is being increasingly exploited as are economically
viable pillars within the mine boundaries.
2. Kopanang Gold Mine
Kopanang
gold mine is located to the west of neighbour Great Noligwa and bound
to the south by the Jersey Fault. Gold is the primary output, with
uranium oxide produced as a by-product, from a single shaft system to a
depth of 2,600m. It almost exclusively exploits the Vaal Reef
Kopanang exploits gold- and
uranium-bearing conglomerates of the Central Rand Group of the
Witwatersrand, the most important being the Vaal Reef. Gold is the
primary commodity extracted with uranium oxide as a by-product. The Vaal
Reef, the primary reef mined, is exploited at depths of between 1,300m
and 2,600m below surface. Minor amounts of gold are also extracted from
the secondary Crystalkop Reef, located about 250m above the Vaal Reef.
Given the complexity of the geology,
scattered mining is employed and the orebody accessed mainly via
footwall tunnelling, raised on dip of the reef and stoped on strike.
Kopanang uses conventional semi-autogenously grinding and carbon-in-pulp
(CIP) technology to process gold. There are two streams of ore into the
plant, one comprised mainly of Vaal Reef ore and the other fed
exclusively with marginal oredump material. Roughly 60% of Kopanang’s
ore is treated in this plant. The balance is sent to the Noligwa Gold
Plant and South Uranium plant by rail for gold and uranium extraction.
3. Moab Khotson Mine
Moab Khotsong is AngloGold Ashanti’s
newest gold mine in South Africa. Stoping operations began in November
2003 with full production achieved in 2010. Given the geological
complexity of the Vaal Reef, scattered mining is employed.Moab Khotsong
is the newest deep-level gold mine in South Africa. It is situated near
Orkney, Klerksdorp and Viljoenskroon, about 180 km southwest of
Johannesburg.
Following the successful exploration of
the Vaal Reef in the Moab lease area, which lies to the south and is
contiguous with Great Noligwa, a decision was taken in late 1989 to
exploit the Moab Mineral Resource. Shaft sinking started in 1991 and
stoping operations in November 2003. The mine is scheduled to reach full
production in 2013.
The main shaft is 3,500 m deep – world’s
deepest continuous shaft – and was commissioned in June 2002 and the
rock ventilation shaft in March 2003. Ore Reserve development on 85, 88,
92, 95, 98 and 101 levels is progressing to plan. Given the geological
complexity of the Vaal Reef, scattered mining is employed.In 2011, the
mine produced 266,000 ounces of gold.The Moab Khotsong mine is to
produce 2.7 million ounces gold over its life of mine which was supposed
to end in 2025.
A feasibility study of the lower mine
(Zaaiplaats) was recently completed. The project will exploit the reef
to depths of 3,455 m below collar. The projected mine extension would
take place and would bring the adjacent Zaaiplaats block into production
therefore another 5.4 million ounces of gold would be produced thus
extending the mine life to 2037.
West Wits
The two West Wits operations, situated southwest of Johannesburg, on the border between Gauteng and North West Province, are:
1. Mponeng Gold Mine
Mponeng, the world’s deepest gold mine
and our flagship operation in the South Africa region, exploits the
Ventersdorp Contact Reef (VCR) at depths of between 2,400m and 3,900m
via a twin-shaft system. Ore is treated and smelted at the mine’s gold
plant. AngloGold Ashanti’s Mponeng mine is located in Gauteng province
of South Africa. It is mined to an average depth of 2,800m-3,400m below
surface and is one of the world’s deepest and richest gold mines with
grades at over 8g/t. It is one of three AngloGold projects in the West
Witts area apart from Savuka and TauTona mines. The name means ‘look at
me’ in the local Sotho language.
Mponeng is located on the north-western
rim of the Witwatersrand Basin. There are seven gold bearing
conglomerates within the lease area, of which two are economically
viable at present. The VCR is a gold-bearing quartz-pebble conglomerate
of intermediate grade, capping the last angular Witwatersrand
non-conformity.
The South shaft deepening project
commenced in 1996 and as a result Mponeng mines the Ventersdorp Contact
Reef (VCR) to the 120 level, which is some 3.4km below datum. Mponeng
mines on average at deeper than 2.7km below the surface. The VCR reef
that Mponeng mines dips at 22º, and has an average channel width of
78cm.
The deepest operating stope is at a depth
of 3.37km below surface. The grade at this operation varies
considerably, therefore a sequential grid mining method is used which
allows for selective mining and increased flexibility in dealing with
changes in grade ahead of the stope. The mine utilises a twin-shaft
system housing two vertical shafts and two service shafts
The TauTona mine exists within the West
Witts area slightly South West of Johannesburg in the North West of
South Africa. “The mine was originally built by the Anglo American
Corporation with its 2 km deep main shaft being sunk in 1957, with
operations starting in 1962.” TauTona Mine or Western Deep Shaft, is a
gold mine in South Africa. At 3.9 kilometers (2.4 mi) deep it is
currently home to the world’s deepest mining operations rivaled only by
Mponeng gold mine TauTona exploits both the Carbon Leader Reef (CLR) and
the VCR via a three-shaft system, supported by secondary and tertiary
shafts sinking to depths of between 1,850m and 3,450m. TauTona’s
infrastructure is to be used to access the remaining Ore Reserve at the
former Savuka mine. A link between the two mines reduces dependency on a
single infrastructure system, including ore passes. The integration of
Savuka into TauTona has been completed and is expected to extend
TauTona’s life of mine. The hoisting of Savuka ore via TauTona is
planned to start in the second quarter of 2015.
The mine consists of a main shaft system
supported by secondary and tertiary shafts. The main mining method is
longwall. TauTona shares a processing plant with Savuka. The plant uses
conventional milling to crush the ore and a CIP (carbon in plant) to
further treat the ore. Once the carbon has been added to the ore, it is
transported to the plant at Mponeng for electro-winning, smelting and
the final recovery of the gold.
Surface Operations
Surface Operations
extracts gold from marginal ore dumps and tailings storage facilities on
surface at various Vaal River and West Wits operations. The hard rock
business processes hard rock material from underground as well as from
marginal ore dumps. Surface Operations also includes Mine Waste
Solutions (MWS) which operates independently and processes slurry
material reclaimed hydraulically from the various tailings storage
facilities. Uranium is produced as a by-product, as is backfill that is
used as mining support in underground mined out areas.
Good progress is being made with the
consolidation of the individual operations in each of these areas into
three operating entities so as to eliminate any duplication of services
and management. This consolidation will have both cost and efficiency
benefits. As an initial step in this process, Great Noligwa mine
employees have been successfully incorporated with those of Moab
Khotsong. The consolidation of the West Wits mines and of Surface
Operations is expected to follow in due course.
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