ON SITE
The blend from the different pits are
fed into a primary crusher (a Metso 120
Jawcrusher) from where it splits into a
secondary crusher (a Sandvik UH430) and
a tertiary crusher (Osborn 44H). From here
the material splits into various slipping
streams and the fine ore component is
split with a high frequency screen into a
-1mm fraction. Odendaal says they are
currently investigating other methods to
do some ultra-fine beneficiation. “We
ultimately end up with a stock-pile of one
and a half million tonnes of unprocessed
fines of less than 1mm which will hold
about 700 000t or 800 000t of sellable ore.
Odendaal, who has a lot of experience
in managing quarries, says the methods
of mining a quarry and an open cast mine,
are usually the same. “Both involve drilling
and blasting the overburden and ore
and disposing of it using specific mining
equipment. However, the difference
between Demaneng and any other quarry
is that the ore body at this mine is a
sedimentary deposit in random pockets of
dolomite. It is therefore not uniform and
sits in an erratic formation which makes it
necessary to follow the higher graded ore
body, so there are fewer consistent neat
bench formations, haul roads and ramps,
and that is the most important difference,”
says Odendaal. Furthermore, quality
control is an important function when
mining iron ore as the grade and quality
are far less predictable than in quarries
where there are large benches featuring
the same quality of material. The quality
control and laboratory work is conducted
as an in house function, affording the
mine speedy turnaround times and priority
access to testing which in turn speeds up
accurate selective mining.
Demaneng is not a conventional mine and there are a number of mini pits on the
property between 60m to 120m deep. Afrimat utilises three of these pits at any
one time and blends the mined products.
Three new CAT980 loaders were acquired for the LOS affording Afrimat the ability to
load a 11 600 ton train in under nine hours.
The mine has also started replacing its ageing mining fleet. The equipment is now
nearing 16 000 hours.
www.equipmentandhire.co.za
Despite the challenges, Demaneng
has gone from strength to strength.
Odendaal says it has a lot to do with
the fact that the operations team at
the mine doesn’t know when to give
up. “This attitude comes from the top
and filters through to the bottom, and
it works for us. The entire company
works together. Attacks the issues and
finds solutions. We also found ourselves
in the fortunate situation where we
managed to secure some of the most
competent industry experts in iron ore
extraction and beneficiation, which
positively shortened Afrimat’s learning
curve in the iron ore sector, concludes
Odendaal.
MARCH 2020
17