Mining in focus
than 0.5mm. Further savings were
achieved by significantly reducing
the quantity of oversize. For
example, only 17% of the material
mined by the surface miners had to
be crushed compared to 26% for the
dozers.
The deposit analysed in the
study contained siderite intrusions,
particularly at the boundary
between seam and interburden.
In the conventional process, this
frequently led to difficulties, because
the siderite intrusions are very hard
and therefore difficult to mine. As
a result, dozers frequently produce
oversized siderite boulders that
cause blockages in the crusher. This
is not the case when mining with a
surface miner.
In addition, working with a surface
miner reduced coal mining losses
and dilution of coal in the mine.
This leads to more product, hence
increased turnover and even an
improved exploitation of the deposit
and thus a better stripping ratio.
Three tasks in a single
operation
Surface miners can cut, crush, and
directly load material onto trucks
or dumpers in a single operation.
This saves time and the additional
cost of purchasing machinery and
fuel. Working with the 4200 SM
in the Australian mine resulted in a
79% reduction in fuel consumption
per cubic metre of mined material.
Labour costs were reduced by 60%
and mining unit costs per ton were
reduced by 60% compared to the
conventional mining method.
The scorecard clearly
demonstrated that, when the entire
process chain is considered, mine
operators benefit from tremendous
cost reductions when using a surface
miner. These reductions are not only
a result of easier processing: The
smaller number of mining machines
www.miningmirror.co.za
and reduced manpower described
above, as well as the avoidance of
additional costs for transporting
and processing waste rock, also
contribute significantly to the good
overall score achieved by the surface
miner.
Not all benefits that result from
the surface miner were part of the
conducted study. Additional benefits
are described below.
Avoiding blasting means
avoiding danger
With surface miners, drilling and
blasting can be eliminated. In other
words, even commodities located
in the vicinity of residential areas,
public roads, or other infrastructure
can be effectively mined. It is
likewise possible to mine resources
located in buffer and safety zones.
In most cases, planning and
execution of blasting work is
associated with considerable
effort, high costs, and regulatory
restrictions. In fact, eliminating
drilling and blasting relieves the
people responsible of a number
of challenges. Mine operators no
longer need to spend time obtaining
the required permits, hiring certified
blast personnel, or compiling
the associated documentation.
Furthermore, getting rid of drilling
and blasting has a very positive
impact on public opinion, meaning
that opencast mining operations can
proceed without causing friction in
a community.
The following are further
advantages of eliminating drilling
and blasting:
• Enhanced safety at the mine
because no explosives need to
be stored;
• No boulder handling
necessary;
• Less impact on the
environment (vibration, dust,
and noise);
•
No interruptions for blasting
(production delays);
• Improved slope stability;
• Reduced rockfall; and
• Better re-cultivation of
embankments.
The use of a surface miner also has a
positive effect on water management
at an opencast mine. The cut surfaces
are levelled and can be cut at an
angle. Drainage is further improved
as a result and water seepage into the
ground is reduced.
Haulage: more tons per hour
The major cost factor in opencast
mining is haulage. Mining with
Wirtgen surface miners produces level
surfaces that serve as stable roadways,
supporting the rapid transport of
material. This increases the transport
capacity of the entire truck fleet. Even
wear on tyres, frame, and suspension
is reduced thanks to the quality of
the roadways, making it possible to
employ standard on-highway trucks.
Surface miners improve
quality and cost-efficiency
In recent years, Wirtgen has
conducted several large-scale field
tests on particle size distribution
and run-of-mine (ROM) material
degradation. In these studies,
coal and sedimentary ore from
eight different pits were analysed
to determine their particle size
distribution. About 8 000t of
material were screened to compare
the material produced by surface
miners with that extracted by
conventional mining methods.
All the studies illustrate that using
Wirtgen surface miners delivers
compelling improvements in final
product quality, cost-efficiency,
environmental protection, and safety.
To fully exploit the surface miners’
profit potential, an analysis should
be conducted when starting the
planning of a mining project. b
NOVEMBER 2018 MINING MIRROR
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