Industry intelligence
Mining waste to improve living
The historic gold fields of Johannesburg are gradually
disappearing as old sites are rehabilitated.
Land rehabilitation specialists Ncamiso
Mining is one of the partners in a
housing development at Fleurhof,
Gauteng. Fleurhof is on the northern
edge of the Witwatersrand Basin in the
Central Rand Goldfield, south-west of
Johannesburg. Ncamiso’s partners are
the City of Johannesburg, Calgro M3,
and Mintails. When completed, the
project will provide housing for about
83 000 people.
“As the Fleurhof land covers old
mining sites and dumps, we knew there
could be high potential to recover gold-
bearing material during the rehabilitation
process. We felt it would be a great loss
to let the mineral wealth in the ground
be sterilised by development,” says
Fikile Mashinini, managing director of
Ncamiso Mining.
Fleurhof is located on the historic
Rand Leases mining area that, together
with Durban Roodepoort Deep (DRD)
mining centre, forms part of the Soweto
Cluster projects, where mining has
been taking place since the discovery
of the goldfields in 1886. Over the past
130 years, there have been up to seven
different gold-bearing conglomerates
mined from the surface, down to depths
in excess of 3 000m. Over 30 million
ounces of gold at a grade of about 5g/t
have been produced from the DRD and
Rand Leases projects.
Ncamiso was previously involved in
the successful rehabilitation of the DRD
cluster, which is currently under residential
development for low-cost housing. The
DRD rehabilitation project yielded over
300kg of gold valued at over R150 000 000.
Ncamiso Mining is currently clearing
and removing contaminated and radioactive
material from an old mine dump where an
electrical substation is planned to be built.
The Department of Energy is financially
backing the City of Johannesburg to develop
the substation to provide future capacity
for further development in the old mining
corridor along Main Reef Road. This section
of rehabilitation alone will enable Calgro
M3 to yield an additional 5 000 residential
units to be developed within the near future.
The scope of work entails the removal
of over one million tons of ground to be
hauled, screened, and processed. Initial
testing, which consisted of grid sampling,
assay results, and bottle roll testing
according to the plan specification, showed
projected gold yields running between
0.6g/t and 1.1g/t to be upgraded by
Ncamiso through screening to 1.8–2.5g/t.
Phase one of the project involves the removal
of all radioactive and contaminated waste from
the area where the substation is due to be built.
The second phase will entail cleaning out and
clearing the wetland mainstream to allow
the easy flow of water in the streams, and
the third phase will be to screen out the fines
from the cladding around the tailing dumps
to ensure there is no material to encourage
illegal mining activity in the area.
“As the ground is located very close to
the residential settlement, we are operating
environmentally safely and there is no
blasting. We clear and mine out the areas
using only earthmoving machinery like
excavators, loaders, screens, bulldozers, and
dump trucks,” says Mashinini.
The gold-bearing material is upgraded
through screening and then hauled from
the area to be further chemically processed
and toll treated by Mintails. Ncamiso
Mining has worked with Mintails on other
successful projects. For the Fleurhof project,
Ncamiso will be working independently
where Mintails treats their tolls at a fee
and then pays Ncamiso for gold yielded.
The gold is then further upgraded at Rand
Refinery to (999AU) pure gold, all of which
is beneficiated locally.
According to Mashinini, the project is
expected to continue for several months
with a hope to continue for the next
five years. There is currently no date of
completion, as it is difficult at this stage to
tell when the project will end.
APRIL 2018 MINING MIRROR
[5]