Operations
O
tjikoto lies about 60km north-
east of Otjiwarongo, the capital
of the Otjozondjupa region,
on the way to the small town of Otavi.
Canadian-headquartered B2Gold acquired
the Otjikoto project through a merger
with Auryx Gold in December 2011. The
company received a mining license in
December 2012 and started construction a
mere four months later. The first gold was
poured two years later in December 2014
and the mine started commercial production
on 1 March 2015.
Mark Dawe, country manager and
managing director of B2Gold Namibia, is
a metallurgist by training, and he and his
team at the Otjikoto Mine have managed
to squeeze the proverbial blood from a
rock. The B2Gold team and the Australian
engineering company Lycopodium have
designed an efficient processing plant that
boasts an average of 98.6% recovery for the
www.africanmining.co.za
YTD 2018 recovery rate (project to date
is 98.4%) — an exemplary performance
under challenging conditions.
Efficient management
Eric Barnard, acting general manager
at Otjikoto and also a metallurgist, tells
African Mining that Otjikoto does not have
the luxury of high-grade ore and therefore,
the strategy is to manage the ore body and
the plant feed as efficiently as possible.
“We have to ensure that we mine the right
grades at all times so that we can meet
our production targets,” says Barnard. A
low-grade operation like Otjikoto is never
able to stockpile high-grade material for
a rainy day. For management, this means
constant planning.
“To make such a low-grade operation work,
one has to mine selectively,” says Peter
Mawoyo, production manager at Otjikoto.
“That includes the mining process in the
two pits, and processing the material in the
plant,” he adds.
“We control the blend into the plant to
ensure correct grade as well as to maximise
recoveries during periods that we are fed
with ore containing a high percentage
of pyrrhotite. One of the criteria behind
the need to carry selective grade control
is to stabilise the percentage of sulphur
contained in minerals such as pyrrhotite,
thereby maximising gold recovery,”
Barnard explains.
Barnard says that when he first saw the
mineralogy of the ore, he did not believe
that recoveries in the high 90s could be
achieved through a conventional mill/leach
gold processing plant. Because the ore at
Otjikoto contains a high component of
gravity recoverable gold (GRG), a plant
was designed with a gravity circuit yielding
exceptionally high recoveries.
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