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GOLD
March 2015
MODERN MINING
23
The flotation section
produces two streams.
One stream, the flotation
concentrate, contains
the sulphides which are
enriched with gold while
the second stream, the
flotation tails, is made up of
lower-grade material which
is treated in a conventional
CIL process (photo: Arthur
Tassell).
new fine-grind process, which involves milling
the slurry material with tiny beads using four
vertical stirred mills (sourced from FLSmidth).
At this stage the milled product, 80 % of which
is smaller than 24 microns, has been liberated
from the sulphides, making recovery of the pre-
viously encapsulated gold easier as it comes
into contact with cyanide during the CIP pro-
cess that follows.
The dissolved gold is adsorbed onto acti-
vated carbon and the ‘loaded carbon’ in each
circuit enters the carbon treatment section
where the gold is eluted from the carbon.
The carbon then returns to the CIL circuit via
a regeneration kiln. Once the gold has been
eluted, it undergoes electro-winning where the
gold is precipitated, calcined and smelted in
the existing smelthouse.
What comes next after the FFG? Pretorius
told the media group that DRDGOLD would
now focus on optimising its high grade opera-
tion further and that it was also planning lifting
production by up to 300 000 tonnes a month
by bringing the 21 Mt Van Dyk tailings dam
resource into the feedstock mix, a low capex
(R23 million) project which would involve
refurbishing five tanks within the CIL section
at Brakpan. Finishing his presentation to the
media, he said DRDGOLD had an operational
profile far closer to that of a processing facil-
ity than a conventional mine and that it would
continue to pursue innovative technologies to
enable it to efficiently and profitably treat the
huge – but increasingly lower grade – resources
to which it had access and which total some
750 Mt of material.
Photos by DRDGOLD unless otherwise acknowledged