Move itorlose it
Assessing mobile plant systems
Damian Connelly
Director/Principal Consulting Engineer
Mineral Engineering Technical Services (METS)
Using trucks can be very inefficient, especially when the
largest trucks can expend up to 60% of their energy just propelling
the vehicle’s own weight, with only 40% used for moving the
blasted rock. Also considering that by default the truck is empty
for half its operational cycle, their inherent inefficiencies become
apparent,” he adds.
In addition to helping maximise productivity and reduce
operating costs, mobile crushing plants can also increase safety
and reduce environmental impact. A noteworthy environmental
advantage of using a mobile system is the elimination of trucks,
reducing noise, vibrations, emissions and fuel.
Safety is also enhanced, as fast moving vehicles play a
significant role in site accident statistics.
Mobile systems will not totally replace the stationary variety
for larger projects; however, where supply is not large, then
mobile plants have the advantage of being able to circulate
between locations and build up stockpiles.
This model also has its
disadvantages. Mobile crushers
have a limited capacity, take time
to relocate (with no production
occurring) and have civil and
structural design difficulties.
Problems with clean-up and dust
issues are also to be considered.
Many of these disadvantages,
however, are primarily with larger
mobile plants.
The advantages of mobile
crushers are primarily lower
capital and operating costs,
enhanced mobility, easier plant
layout, as well as environmental
benefits. Mobile plants have also
opened up toll crushing to further
reduce capital expenditure for
small deposits, with the cost being
seen in the operating cost.
There are key project aspects that need to be weighed up when
considering this plant application. It is essential to consider design,
operational, maintenance, life of mine, expansion and climatic
aspects, as these will all have an impact on the project success.
METS, using testwork analysis and subsequent modelling, is able
to define a suitable design for a mobile crushing operation for
plant integration.
Mobile crushing plants are currently being used in several
applications, from smaller operators through to large-scale
companies. Operations that feature the use of mobile crushing
plant include:
-
Alcoa’s operations in Pinjarra
-
BC Iron’s Pilbara operations
-
several BHP operations (Yarri, Yandi and Area C)
-
four Rio Tinto locations, including Nammuldi, Brockman and
two at the West Angelas operation.
A 5Mtpa mobile crushing plant in operation at a Pilbara-based iron ore project
As the resource sector becomes tougher in a climate of rising
costs and cyclical metal prices, mining organisations need
to continue to improve efficiencies and do more with less.
Exploring the option of a mobile plant may prove beneficial for
cost conscious organisations. Newly designed mobile crushing
and screening plant systems have the advantages of mobility,
flexibility, economy and reliable performance, making them very
appealing for small to medium sized projects or projects where a
number of resources are separated by distance.
While the concept of mobile and semi mobile primary crushers
has been around for a long time, starting with early batch
crushing operations, many of these were very low throughput.
The basic components of a mobile tracked crushing plant
are almost the same as for a stationary plant but with the added
advantage of complete mobility, even up slopes as steep as a
1:10
incline. Where track-mounted crushing systems really come
into their own is their ability to be positioned right at the work
face, and to then be relocated, for example when blasting, under
their own power in minimal time (20 minutes).
The other leading benefit of mobile applications is in reducing
project costs.
Crushing equipment to be sited at the rock face is intuitively
a good solution, in terms of optimised productivity and lower
operating costs,” says Damian Connelly, METS Director/Principal
Consulting Engineer.
Minesite 2013
149