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January 2017
MODERN MINING
59
Top projects
Acting Mining Manager
Mario Cloete on site at
Gamsberg.
as a substantial amount of productive capac-
ity has been taken out of the market over the
past couple of years and has not been replaced.
“We’ll be the first new mine to start-up in what
is increasingly a market in deficit,” she says.
“The zinc price will obviously incentivise oth-
ers to bring on line new mines but at this stage
we’re way ahead of everyone else.”
One spin-off of the price plunge in early
2016 was that it motivated VZI to look at ways
of cutting Gamsberg’s capital budget. “We were
originally planning to owner mine at Gamsberg
but have now decided to use a mining contrac-
tor and this, of course, is a less capital intensive
approach,” says Naidoo. “We’ve also renegoti-
ated various contracts and re-engineered the
project to deliver substantial savings. All told,
we’ve reduced the capex by US$200 million –
which is an amazing achievement.”
Updating on the current status of the project,
Kumar – who used to be the GM at Skorpion –
says the ground-breaking ceremony was held
in July 2015 and that there are now around 300
workers on site, with this figure expected to
peak at 1 500 at the height of construction.
“Gamsberg is an inselberg that extends
about 220 m above the surrounding ‘flats’,” he
says. “We will be mining on top of the insel-
berg, so we’ve had to build roads to access the
mining area. We appointed a local Northern
Cape contractor, Roux Mining, to carry out
this work and to establish the starter pit and
they are making very good progress. Roux is
what we call the ‘pre-start contractor’ but we
have now appointed our bulk mining contrac-
tor, Aveng Moolmans, who will soon mobilise
to site. There’s a huge amount of pre-stripping
required to expose the orebody – close to 70 Mt
– so we will only start producing ore in the
middle of 2018. Although most of this pre-
stripping will be the responsibility of the bulk
mining contractor, Roux has made a start on it
and 12 Mt has been moved already.”
According to Kumar, the mining operation
at Gamsberg will be a conventional load-and-
haul exercise. “We have asked the contractor
to use the latest technologies in drilling but
other than this there is nothing unusual about
the approach being adopted. The strip ratio in
Phase 1 is about 7 to 1 so to achieve our targeted
ore production we’ll be moving over 30 Mt/a.
The explosives supply has been contracted out
to BME, who have been performing that func-
tion since 2015 when work first started on site.”
Moving to the process plant, Kumar
describes the flowsheet as “conventional with
some tweaks” and says it will include primary
crushing, milling (via SAG and ball mills),
flotation and dewatering. “We have three stages
of flotation, the first to take out carbon, the sec-
ond to remove the lead and the third for zinc,
with the final product being a 48 to 52 % zinc
concentrate,” he notes. He adds that the tail-
ings facility will be constructed to the highest
standards and will be HDPE lined.
The EPCM contractor for the processing
facility (and related infrastructure including the
power and water plants) is ELB Engineering,
who will be using – for the first time in a zinc
application – the new staged flotation reac-
tor (SFR) technology of Canada’s Woodgrove
Technologies in the plant. Benefits of the tech-
nology over conventional mechanical cells
reportedly include a much more compact foot-
print, reduced power and air requirements, less
instrumentation and reduced wear and mainte-
nance costs due to lower impeller tip speeds.
As regards the power required, VZI has con-
cluded an agreement with Eskom to supply
40 MW. The bulk water will be sourced from
the Orange River, just 33 km to the north of the
site. BMM already draws around 13 Mℓ a day
from the Orange for its current operations and
the new project will essentially double up on
this. Additional housing will also be needed
in the town of Aggeneys as the Gamsberg proj-
ect will generate over 500 new permanent jobs
once in full production.
While Gamsberg, like any big mining project,
has its share of technical challenges, perhaps
the biggest challenge of all is its location in the
arid Northern Cape in an area that has been
identified as a biodiversity hotspot. Explains
Naidoo: “Gamsberg lies in the Succulent Karoo
Biome – one of only four hotspots in South
Africa – which is home to 6 000 plant spe-
cies, and it also forms part of the Bushmanland
ZINC
“The zinc price
will obviously
incentivise others
to bring on line
newmines but at
this stage we’re
way ahead of
everyone else.”