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May 2017
MODERN MINING
35
feature
CRUSHING, SCREENING
AND MILLING
commissioned at coal mine
Above:
A 625 Series
primary sizer (cap machine)
in MMD’s workshops in
Longmeadow ready for
dispatch to a gold mine in
Burkina Faso.
Above left:
The fourth
semi-mobile station at
Exxaro’s Grootegeluk
open-pit coal mine.
solutions for the underground UK coal indus-
try, initially designing and manufacturing
in-line breakers. In 1980 he invented the twin-
shaft mineral sizer which provided a technical
breakthrough in mineral reduction.
The original mineral sizer developed by
MMD was specifically designed to work in the
confined space of underground coal mines and
was able to handle tonnages of up to approxi-
mately 1 500 t/h. Building on the success of this
original 500 Series machine, MMD now has a
wide range of sizers with the biggest machine
being the 1500 Series which was first supplied to
operate within the oil sands industry in Canada.
Depending on the sizer shaft centres,
machines can be configured for primary, sec-
ondary or tertiary crushing and all can be
customised to the client’s requirements. The
full range of MMD sizers can also be supplied
in fixed, mobile or semi-mobile configurations,
with units being wheeled, tracked or mounted
on skids.
Detailing the advantages of MMD’s mineral
sizers, Nel says that they are very compact
and lightweight compared to more traditional
crushers of the same capacity. He also points
out that they have the ability to process not just
hard, dry rock but also soft, abrasive and sticky
materials which can often cause problems for
conventional crushers. Moreover, the output
from the machines is an accurately sized prod-
uct with minimal fines.
Complementing its mineral sizers, MMD
has a range of heavy-duty apron plate feeders
to convey raw material to the crushing plant.
The main features of the apron feeders are
the heavy-duty chains and rollers which are
attached to the main frame and which are
manufactured by Caterpillar. The design of the
feeders is such that impact energy is reduced
to a minimum. Four feeders are available, des-
ignated the D4, D7, D9 and D11 and offering
effective widths from 1 500 mm to 4 000 mm.
Nel says that MMD Mineral Sizing (Africa)
is increasingly positioning itself as a turnkey
solutions provider rather than just a supplier.
“We have strengthened and expanded our
local in-house design and engineering capa-
bilities considerably in order to provide faster
turnaround times and at the same time pro-
vide engineering solutions which comply with
customers’ specific specifications and unique
requirements,” he says. “We’re also becoming
involved during earlier stages of our customers’
projects and every so often we’re contributing
to the pre-feasibility and feasibility stages. In
addition, we’re teaming up where appropriate
with other suppliers during such phases.”
In another development, MMD has installed
a custom designed and manufactured dust
hood on one of its semi-mobile plants at the
request of the client in order to control the dust
generated from the dump trucks that tip raw
material into the semi-mobile sizing station.
“The dust hood is very effective and the client
is considering whether to fit hoods to its other
stations,” says Nel.
Despite the recession in mining, MMD