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FINDING THE BEST
PROCESSINGROUTE
DAMIAN CONNELLY
DIRECTOR/PRINCIPAL CONSULTING ENGINEER
MINERAL ENGINEERING TECHNICAL SERVICES (METS)
flotation and agglomeration (pelletizing, sintering, briquetting, or
nodulizing). Engineering consultancies play a significant role in
assisting miners in developing the most appropriate beneficiation
method for their ore body. Testwork and simulation are key tools
in the metallurgy kit bag to find the best processing route from a
capital and operating cost viewpoint. Engineers are able to take
testwork data and “interpret” the best route for processing. One
of the tools available to engineers involves using their experience
and marrying this to simulation packages that can model various
options for a processing plant; taking into account contributing
factors identified in the testwork stages.
Simulation is a powerful tool for predicting outcomes of process
plant operations and can answer the “what happens if” scenarios.
This can include process plant behaviour, maximising energy
efficiency, de-bottlenecking flowsheets and even optimising of
stockpile sizes to suit a specific footprint. This however, does
not mean the end of the process engineer. It also takes the skill
of experience to know the limitations of a package and how the
promises match reality and how accurate the predictions are.
Even though the
simulation might not
get it exactly right, the
outcome gives a far better
prediction of a complex
problem than otherwise
would be the case. It is
very good at ranking
options so that less
favourable options are
discarded very quickly.
In this regard there are
no better choices.
The cost of the
software is relatively
high
compared
to
everyday products in
use and even more
challenging is the cost
of training personnel
to become competent in using it, resulting in this type of work
being outsourced to consultants. This results in far better value for
money than trying to “do it yourself”.
The connection between simulated results and the real
world can be evaluated using data from operating plants. In this
regard the results have proven to be surprisingly accurate. As an
example, the modelling of a WA comminution circuit where the
ore hardness had increased resulted in an increase in throughput
some 4% higher than had been predicted, a result which no one
was unhappy about. Another example of modelling a new ore
through an existing semi-autogenous grinding (SAG) ball pebble
crusher circuit predicted that the circuit required changes to
optimise throughput and that the pebble crusher was not required.
In both cases the experience of the engineers proved to be key.
There is a growing challenge to design more efficient
beneficiation plants to make emerging lower grade iron ore bodies
into projects. While there are simulation packages, the role of
the experienced process engineering to make these visions into
projects will be here for some time to come.
EXAMPLE FEASIBILITY STUDY LEVEL DESIGN OF A PROCESS PLANT
ith the demand for construction projects still
requiring vast volumes of steel, this has seen
the gradual depletion of easier processing
iron ore bodies on a global scale. New projects
are becoming more capital and operating cost
sensitive and as such, the role of process engineering consultancy
firms to find more efficient plant designs has never been stronger.
One of the traditional techniques for liberating the ore from
the gangue (or in lay speak – mineral from waste) is beneficiation.
Beneficiation “upgrades” the ore. It is an integral part of the
science of mineral processing, and the concept that this science
encompasses is relevant to the field of iron ore production. In
general the objective of beneficiation is to remove 1) unwanted
minerals or 2) particles of unsuitable size or structure. Compared
to the other extractive processes, it is relatively inexpensive.
Beneficiation of an iron ore can be considered in different
methods such as milling (crushing and grinding), thickening,
filtration, sizing, gravity concentration, magnetic separation,
W
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