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January 2016
MODERN MINING
63
Top projects
COPPER
SA’s grand copper heritage
Above:
The open pit
at Palabora. Note the
subsidence of the pit’s
north-west wall.
‘early works’ – the vital development of a twin
decline and supporting engineering infrastruc-
ture from Lift I down to the new orebody.
“This was a significant investment by share-
holders, showing the confidence they had in the
project, even in the early stages,” said Fouche.
Conducted as a close collaboration between
the mine and contractor Byrnecut South Africa,
the twin declines of 3,6 km each preceded
apace, achieving rates of advance of 10,5 m per
day; the process also allowed for an upgrade
of electrical infrastructure, services
and ventilation. One decline will
be for services, while the other will
house the switchback rock conveyor
carrying ore to the base of the verti-
cal shaft at Lift I level. A temporary
crusher is to be installed at the
base of the conveyor to be used for
development tonnages and first pro-
duction; at the other end, ore will be
lifted to surface in the shaft.
The Lift II mining footprint is
now being developed from the twin
decline, with access drives based on
the classic herring-bone block-cave
design used in Lift I. Three levels
will be developed, linked to each
other by connecting ramps:
the undercut level is where the
orebody is drilled and blasted so
that it ‘caves’ into the drawbells;
the extraction or production level
about 18 m below, which receives the frag-
mented rock through the drawbells; and
the ventilation level, 25 m below the produc-
tion level.
While Palabora’s carbonatite rock mass has
the advantage of well-delineated ore, it is also
considerably harder than the kind of rock nor-
mally mined by the block-cave method – in the
kimberlite of diamond mines, for instance.
“We pioneered some ground-breaking tech-
nology during the Lift I phase, as this was the
Below:
Layout of the
Palabora mine showing the
open pit and Lifts I and II.