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July 2016
MODERN MINING
27
COAL
Drill rig operating at the Mabesekwa project.
and that the project was being developed
to supply electricity to South Africa in
terms of the cross-border procurement
programme.
The project calls for two or four gen-
erating units, each with an output of
150 MW. It is expected that circulat-
ing fluidised bed boilers will be used.
Due to the fact that Botswana is a water
scarce country, the project would deploy
a dry cooling system.
The water supply strategy includes
the construction of a pipeline from the
Shashe Dam, approximately 60 km from
the project site, which will provide raw
water to the water treatment plant and
other plant and equipment as required.
A nearby wellfield with 18 boreholes
and sufficient capacity will provide a
back-up water supply solution.
A positive coal mining pre-feasibility
study (PFS) by Ukwazi Mining Solutions
to define the mine configuration and
technical and economic potential of the
Mabesekwa coal project was completed
in August 2015.
The coal supplied is expected to have
ash content of less than 30 % and pro-
duce an approximately 17 to 19 MJ/kg
product which will be transported to the
power plant by a conveyor system. The
mine will be a conventional open pit.
Shumba’s second advanced proj-
ect – the Sechaba Coal Independent
Power Producer (SCIPP) project – envis-
ages a 300 MW coal-fired power plant
being developed to supply electric-
ity to Botswana and other countries
in Southern Africa. At this stage
Shumba Energy is the sole developer
but Phumaphi told delegates to the
Gaborone conference that the company
was in discussions with several poten-
tial strategic partners.
Based on the completed conceptual
design study undertaken by Parsons
Brinckerhoff Power, the SCIPP power
plant is envisaged to be configured as
a 2 x 150 MW (gross capacity) coal-
fired facility. The contracted net power
available would be approximately
270 MW after deduction of auxiliary
consumption.
The boiler furnace will be of the cir-
culating fluidised bed subcritical natural
circulation type with one steam genera-
tor provided for each unit, with dry air
cooled condenser technology. Sulphur
Oxide (SOx) control will be achieved by
in-situ SOx capture by limestone dosing
in the boiler furnace. Particulate matter
control will be achieved with electro-
static precipitators.
The estimated in-situ coal resource at
Sechaba is 1,14 billion tonnes, predomi-
nantly contained in two main coal seams
– the upper Taukome Bright Seam (TKS)
and the lower Morupule Main Seam
(MMS). Average seam thicknesses are
2,6 m (TKS) and 3,7 m (MMS) with the
coal found at average depths of 30-100 m.
As with Mabesekwa, Ukwazi has been
responsible for a mining pre-feasibility
study for Sechaba which was completed
in 2014. The selected mine configuration
targets surface and mining infrastructure
and an underground mine to ramp up
to 1,5 Mt/a in the shortest possible time
frame and at the lowest cost. After this
production level has been established, it
is envisaged that a phase two expansion
could increase the annual production to
3 Mt/a. Appropriately detailed mine lay-
outs for the boxcut and the underground
mines for MMS and TBS were prepared
and major equipment sized.
Summing up Shumba’s ‘offering’,
Phumaphi said Botswana and the wider
Southern African region offered few
advanced IPP opportunities, which
placed Shumba – with its two advanced
projects – in a very favourable posi-
tion. He said both projects had excellent
infrastructure access and both enjoyed
strong support from the authorities in
Botswana. He concluded by saying that
Shumba was hoping to be providing an
initial minimum supply of 265 MW to
the grid by 2020.
Photos courtesy of Shumba Energy