coal
51
07.13
Bulk sample pit on the farm Tanga 849 MS.
started prospecting and exploration drilling. Up until
2012, out of a total of 506 boreholes, CoAL has drilled
a total of 214 boreholes within the project area.
Between August 2010 and April 2011, CoAL ex-
cavated a boxcut on the farm Tanga 849 MS. From
this 45 849 t of ROM has been processed, producing
21 800 t of coal, some of which was transported to
Exxaro’s Tshikondeni coking coal mine for process
testing. This bulk sample was excavated in order to
confirm the hard coking coal qualities and coking
product quantities and to test various processing op-
tions for the coal.
Mine plan
The project has been divided into three separate min-
ing areas for technical, logistical and practical rea-
sons, namely East Pit, Central Pit and West Pit. The
East and Central pits are separated by the Siloam fault
with a displacement of approximately 50 m. The Cen-
tral and West pits are separated by an area of steril-
ised coal associated with the village of Mudimeli.
Mining will be staggered, commencing in the East
Pit followed by the Central and West pits. This ap-
proach enables CoAL to optimise the resources re-
quired for mining over the LOM, and also provides
a consistent balance of ROM quantity and quality
through to the plant. First production is scheduled
for month 26 from project start.
Development of the East Pit will include plant and
infrastructure components which will cater for the
production volumes from the other pits.
Makhado contains a number of coal seams with
their dips requiring the walls of the pit to be benched
for stability at 15-m intervals and the overburden and
interburden to be placed on surface until such time as
concurrent backfilling can begin. This geological set-
ting is amenable to the proposed opencast large truck
and shovel mining method.
To achieve the required steady state production
rate, the mining build-up schedule requires over-
burden waste material to be pre-stripped in the ini-
tial box-cutting and ramp-building stage to establish
an in-pit coal inventory before coal extraction pro-
ceeds. Thereafter, for the following five years there
will be a low to moderate annual overburden strip
ratio of 1:3,3.
A Whittle pit optimisation exercise was used to de-
velop the economics of the coal deposit in relation to
its technical aspects. This allowed the selection of the
optimal shell for each of the pits based upon their un-
discounted NPV. The practical pits will extend from
an average depth of 30 m below surface (to take into
account the negative effect of oxidation on the coal in
the upper layers) to maximum pit depths of 197 m,
161 m and 121 m for the East, Central and West pits,
respectively.
The subsequent increase in stripping volumes, up
to a strip ratio of 1:4,1 annually, occurs concurrently
with the second pushback in the East and Central
pits. Due to the friable nature of the coal and its ori-
entations, ‘through seam blasting’ technology will be
employed to break the parting and coal seams. This
tried and tested blasting technology will minimise
coal losses as well as coal contamination during the
loading process.
Crusher and screening systems will be located to
the south of each of the pits. The coal processing
plant will be located to the south of the East Pit. The
processing plant site was selected to minimise haul-
age distances as the East Pit is the largest pit with the
greatest portion of coal reserves.
The operational expenditure (opex) is based on a
contractor mining model with CoAL being respon-
sible for mine planning, geological and geotechnical
controls, as well as cost management.
Recent work carried out on detailed mine planning
has enabled a coal Reserve Statement to be issued by
CoAL, confirming a total of 173 million ROM tonnes
available to be mined for the project.
Process plant
A coal processing plant has been designed capable
of handling the 12,6 Mt of ROM per annum needed
in order to produce the estimated 2,3 Mt/a of hard
coking coal and 3,2 Mt/a of thermal coal. The hard
coking coal will have an ash content of 10 %, whilst
that of the thermal coal will be 30 % ash.
A Process Design Criteria (PDC) completed by DRA
Mineral Projects was used as the basis for engineering
studies and the coal handling process plant design.
The site plan, plant layouts, equipment lists and as-
sociated utilities are at an advanced stage.
The proposed processing route will see ROM being
de-stoned in the pit by scalping off the +50 mmwhich
will be discarded. The -50+0 mm stream, which is es-
timated to be approximately 77 % of the mined ROM
delivered to the tip, will be conveyed to the plant
feed stockpile as feed to the hard coking plant.
The processing plant consists mainly of three pro-
cessing sections:
A double-stage Dense Medium Separation plant for
both de-stoning and beneficiation of the hard cok-
ing coal and the thermal product, achieved through
a high gravity wash followed by a low gravity wash
(for the coarse size fraction of -50+1 mm).
Afines (-1+0,15mm) circuit comprising a low gravity
Reflux Classifier process for the production of the
coking coal and a high gravity Reflux Classifier for
the production of the thermal product.
An ultra-fines (-0,15 mm) circuit of Jameson column
flotation cells for the production of the coking coal
and a potential thermal product.
The plant has been designed to optimise yields
