MINE EXCURSION
gangue is mainly iron oxide, which is hematite, and silica. “To
increase the temperature, several methods can be used, but all
involve energy input. Electricity springs to mind immediately, but
electricity is only economical in small amounts. The most effi cient
and the most economical way to satisfy the heat requirements is
with coal-fi red boilers. To generate enough steam, we require low-
pressure boilers,” says Brits.
The mine has installed four boilers. Each of the boilers produces
about 10 tonnes per hour of steam. The plan is to have three
boilers operating at any one time and then have a fourth boiler
on standby.
Mining two deposits
Wagner says that they have started mining both the Outwash
Fan and Plattekop deposits. Most of the initial overburden
unearthed from the Outwash Fan deposit was used in the
construction of the tailings dam. Lower grade ore from the
Outwash Fan was put through the plant fi rst before the
deposit at Plattekop was exposed, which, according to Wagner,
produces a higher-grade ore. All mining currently takes place in
the Plattekop pit.
Initially, in the fi rst year, mining will focus mainly on the
Plattekop orebody with smaller tonnage coming from the
Outwash Fan orebody. In the second year, mining on the
Outwash Fan deposit will start in earnest and for the next nine
years the plant will receive a blended product from both pits.
Thereafter for about seven years, the plant will be fed from a
higher-grade shallower portion of the Outwash Fan deposit as
the Plattekop deposit will be worked out. In the last three to four
years, mining will be concentrated in the deeper portion of the
Outwash Fan pit. There is a real prospect of extending the life of
mine from Wiltin, the third ore body on Nokeng’s license area.
Wiltin is only partially explored at this stage.
“We do not know too much about Wiltin, but it looks like a large
orebody, and it off ers potentially a very viable alternative,” says
Wagner. The hills above the processing plant are rich in fl uorspar
and at Wiltin, it outcrops in a number of places very close to
the surface. “We have done some geophysics, but we still don’t
know the full extent of the ore body. However, it does appear to
be an extension of the Plattekop ore body and has a similar sort
of grade to Plattekop,” says Wagner.
The ore is drilled, blasted, loaded, and hauled from the pits
to the mineral processing facility. Outwash Fan is about one
kilometre from the plant, while Plattekop is just under three
kilometres. The open pit mining is done by medium scale
mining contractor Andru Mining, which uses two excavators
in the pit and four 30 tonne ADTs to haul the material to the
primary crusher.
Wagner says that the mine is not yet running at full capacity and
that there are elements of the plant that are capable of handling
a lot more feed. “We believe we can get the plant up to 220 000
to 250 000 tonnes per annum output within two to three years
after startup, and then we still need to look at Wiltin as well,” he
says. The company plans to continue exploration of the Wiltin
deposit over the next two years. “We know that the deposit
outcrop, which is between 15m to 20m thick on surface, is a
very signifi cant deposit, we just don’t know the extent, Wagner
explains. Furthermore, Wagner adds that there could be other
substantial deposits in the hills.
There are not many other operating fl uorspar mines in South
Africa, with Nokeng’s neighbour, Vergenoeg, being the most
signifi cant. Vergenoeg is jointly owned by Spanish fl uorspar
producer Minerales y Productos Derivados SA (Minersa) with an
85% share, and MEDU Capital (15%). The mine has a production
capacity of 240 000 tonnes per annum (tpa).
The resources at the Plattekop and Outwash deposits at Nokeng
are world-class in terms of grade, low deleterious elements,
bulk type deposits as opposed to vein-type deposits and ease
of mining. South Africa hosts about 17% of the world’s fl uorspar
reserves. Currently the global fl uorspar market is about
6Mt a year.
Nokeng’s concentrator will produce about 180 000t of acid grade fl uorspar (97% pure fl uorspar) and 30 000t of metallurgical grade fl uorspar annually
from run-of-mine fl uorspar ore production of 630 000t.
www. africanmining.co.za
African Mining Publication
African Mining
African Mining November 2019
29