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April 2016
MODERN MINING
29
COVER STORY
Personnel from drilling
contractor Major Drilling
studying drill core during
the exploration phase.
D
r Danie Grobler, Head of Geol-
ogy for Ivanplats, recalls that
the deep drilling of the Flatreef
involved as many as 30 drill rigs
on site simultaneously with over
700 km of core from more than 1 200 holes be-
ing generated in the period from the late 1990s
to 2015 – all of it now stored at Ivanplats’ of-
fices and core shed in Mokopane. Some of the
drill intercepts during this campaign were
phenomenal and in October 2013, for example,
Ivanhoe’s Executive Chairman, Robert Fried-
land, and its CEO, Lars-Eric Johannson, report-
ed what they described as an “unprecedented
90 m intersection” of 4,51 g/t of platinum, pal-
ladium, rhodium and gold plus 0,37 % nickel
and 0,20 % copper. This included a 40,79 m
section grading 6,88 g/t 4PGE.
The Flatreef’s indicated mineral resources
total 214 Mt grading 4,1 g/t (3PE+Au), 0,34 %
nickel and 0,17 % copper at a 2,0 g/t (3PE + Au)
cut-off grade containing an estimated 28,5 mil-
lion ounces of platinum, palladium, gold and
rhodium, 1,61 billion pounds (725 747 tonnes)
of nickel and 794 million pounds (360 152
tonnes) of copper. The current resource was
published in 2013 and
a new mineral resource
estimate is expected later
this year.
The geological interpre-
tation of the Platreef (and,
by extension, the Flatreef)
and the degree to which
it correlates with the
Merensky Reef is a highly
technical subject – and a
matter of some controversy
in the geological commu-
nity – but Grobler is in no
doubt that the Platreef is,
to all intents and purposes,
identical to the Merensky.
This view was more
formally expressed in
a paper he co-authored
with Dr David Broughton,
Ivanhoe’s Executive VP,
The Platreef –
the Merensky in all but name
The Platreef project has been the subject of one of the most intense exploration programmes ever
undertaken for a mining project in Africa. The initial focus was on near surface mineralisation but in
2007 a deep exploration programme was launched which led – three years later – to the identification
of the Flatreef deposit, which lies within a flat to gently dipping portion of the Platreef mineralised
belt at a relatively shallow depth of 700 m to 1 100 m below surface (over a strike length of 6 km).
Exploration, and Tim Dunnett, a senior geolo-
gist with Ivanplats, presented at PDAC in 2014
in which it is stated that the Flatreef can be
viewed “as a hybrid deposit type with internal
features and stratigraphic correlation consis-
tent with the Merensky Reef, and economically
attractive thicknesses (the Flatreef indicated
resource averages 24 m thickness at a 2 g/t 4E
cut-off) typical of Contact-type deposits.”
Cross section through the
Flatreef. The highest grades
occur at the top of the
Flatreef.