Mine excursion
available. With three excavators, our target
is to mine about 10 500 cubic metres per
day in two 12-hour shifts. Khanye currently
operates until six on a Saturday morning on
the mining operations, but we’ve applied for
a continuous mining permit to enable us to
mine on Sundays if required.
Unearthing the coal
CMS will use excavators and ADTs to load
the coal, thus about three to four trucks per
excavator, depending on the haul distance
and turnaround time. “Because all three
excavators are working close to each other
you can swop trucks. Operators are trained
to identify where they are needed the most
when they arrive at the face. Our control
room system allows the operator to report
on an hourly basis what they have loaded
(topsoil, shale, clay or coal). The system works
well because South Pit is small. However,
if there are 60 trucks and more excavators,
you do need a more fixed and rigid system,”
Thompson adds.
Canyon Coal does all the blasting at
Khanye in-house, but the drilling is done
by a contractor called MEM. The company
uses BME’s electronic blasting system. At
the moment, they are drilling up to 13 000m
per month including overburden, parting and
coal. Thompson says that there is a lot of clay
in the area and they have historically only
been able to drill about 3 000m to 5 000m
per month. “In the South Pit, however, there
is a thick sandstone band, so our drilling
increased more than three times last month,”
he says.
When Mining Mirror visited the site,
the mine had blasted through the sandstone
belt to expose 2 Seam coal. The sandstone
material is used to build the mine’s haul
roads. Blasting takes place as and when
needed, but on average once or twice a week.
Mining in the soft clay material in all three
pits has limited the number of blasts required,
but the clay also provides a challenge.
The first coal seam (2 Upper Seam) in South Pit, is encountered at the bottom of the sandstone, about 9m
from surface.
Thompson says the clay causes what
the miners refer to as “carry back” in the
haul trucks. In other words, the clay gets
stuck in the bin and needs to be cleaned
out on a regular basis. “We have dedicated
TLBs in the pits that clean the back of
the trucks on a regular basis. If they don’t,
the trucks deliver half loads,” explains
Thompson.
Processing the material
The distance from the South Pit to the
main processing plant is about 1.6km,
which will be the longest haul, but the
team is mining progressively towards the
plant, which means the hauling distance
will be reduced over time. There is a
ROM tip area between the two plants
from which both plants are fed. The
bigger plant is a lot more advanced than
the small modular plant, which produces
an RB3 product of zero by 50mm.The
new plant will normally target a 25.5
CV, but that will change to a 27 CV at
certain times, as some coal seams are of a
better quality than others, which means
the products will be blended to produce a
high quality export coal.
Khanye’s new plant is the first of
Canyon Coal’s larcodem plants built
by contractor Obsideo and operated by
Isimilo DBO, which consists of larcodems
instead of the traditional drum plant, and
a filter press to process the slurry. The coal
mined in the pit is fed into the ROM feed
bin. From there it goes through a primary
crusher, then into a secondary crusher
before it splits off into the larcodem that
produces large and small nuts. After that
the material enters a cyclone that handles
the peas and the duff. Thompson explains
that a secondary stage wash capacity is
planned to be built within the main plant
Khanye recently acquired a brand new fleet of Volvo Articulated Dump Trucks (ADTs).
www.miningmirror.co.za
JUNE 2019 MINING MIRROR [17]