COMMINUTION
testing and specific near-field monitoring
methods from production blasting operations
employing analytical models, which evaluate
explosive energy, shock decay as well as
characterisation of rock and ore masses in terms
of dynamic modulus and strength along with
structure”, iRing said.
Williams said: “Our break model (Break
Analyzer) doesn’t, per se, provide fragmentation
analysis, but, as a result of an optimal pattern for
the rock and explosive type, it will give you very
good fragmentation; we just cannot quantify
what it is.
“That is part of the [Crush It] Challenge too;
we have to develop a model to help quantify this
so people can get these fragmentation
distributions as they look to bypass the primary
crusher,” he said.
Preston said: “I think we have a really good
shot of making the underground blasting
environment so precise that it will benefit not
only underground mines that are in business
today, but orebodies that will be going deeper in
the future and require precision blasting to both
extract the ore and retain the host rock for
support.”
There are other potential applications for the
group’s work, according to Williams.
“All of our models are physics-based and
mathematics-based reverse principles, so there
is no reason our technology wouldn’t work on
surface,” he said.
OEM/consultant expertise
It is not just iRing that thinks mining companies
would do well to look at drilling and blasting
practices to optimise downstream comminution.
Can Özer, Senior Process Technology Engineer
at Metso, told IM: “One of the strengths of Metso
is its capability to optimise drill and blast design
for the installed comminution circuit. Hence,
most of our comminution projects involve drill
and blast optimisation to seek the most
beneficial rock fragmentation delivered from the
pit to the comminution plant.”
Özer said the level of confidence in these
projects has been improved by implementing
Metso’s SmartTag™ system. SmartTag can be
used to track ore from the mine into the plant,
correlating ore characteristics with important
operating parameters in the mine and processing
plant, such as ore dilution, ore losses,
fragmentation, throughput and energy
consumption.
This, Metso said, provides an understanding of
how different ores affect mine and plant
operation and the final product. “Operating
parameters and control strategies in the mine
and processing plant can be adjusted and
optimised for different ore types, thereby
reducing costs and increasing profitability,” the
70 International Mining | APRIL 2019
Metso’s Global Consulting and Laboratories
Manager, Suzy Lynch-Watson, says the
introduction of HPGR/HRC technology (a Metso
HRC3000, pictured) to replace SAG mills in
many metalliferous ore operations was gaining
traction and bringing down energy consumption
in the comminution circuit
company said.
Such a system creates a link between the ore
audited in the drill and blast process, and the
same ore surveyed in the plant, according to
Özer. “Modelling and simulation tools are
combined with our drill and blast experience to
quantify the benefits of changing the blasting
practice for the benefit of the overall process,”
he said.
The SmartTag system also comes in handy
when measuring dilution or loss and improving
blending strategies, Özer said.
This integrated mining approach from
equipment providers is being put forward as the
way to reduce energy and water consumption by
many in the industry.
As Keogh said, “When you take individual
processes, improvements in the order of 5-15%
are often possible. But when you integrate
changes across the mining value chain, that’s
powerful. Optimising the process can result in
much larger gains.
“The targets of 30% to 50% improvement are
beginning to look achievable at some sites, and
that’s exciting for industry’s future.”
CEEC outlines just some of the areas its
member companies are focusing on:
“Advances in blasting (improved
fragmentation), pre-concentration and ore
sorting, coarser grind applications (size-based
grade engineering, fluidised bed flotation, heavy
media separation), replacement of inefficient
SAG mills with efficient comminution
technologies (such as high pressure grinding
rolls (HPGR)), novel/hybrid configurations (AG
milling, pebble milling, HPGR circuits) and mine-
to-mill optimisation are delivering tangible
results.”
Hatch (CEEC Sponsor) Mineral Process
Engineering Consultant, Kristy Duffy, said many
comminution circuits could be made more
energy-efficient by modifying the design or
operating conditions.
“Use of alternative comminution machines, for
example, HPGRs, better utilisation of pebble
crushers, stirred mills, less use of AG/SAG mills,
and correct selection and operation of classifiers,
particularly hydrocyclones, can significantly
improve the efficiency of the overall circuit,” she
said.
“As early as 2002, [Metso’s] Valery and
Jankovic proposed that combining improved blast
design with a comminution circuit using HPGR
and Vertimills could reduce energy consumption
by more than 40% compared with a conventional
blasting/grinding circuit,” she said. “The energy
savings are a result of higher intensity blasting
and the high efficiency of the HPGR and Vertimill
technologies.”
Metso, in its 2018 annual report, said a review
of the Vertimills currently in operation around the
world and a comparison of their efficiency and
media consumption relative to a ball mill,
showed around 1.48 million MWh of energy was
saved and 652,000 t of CO 2 emissions were
abated in 2018. This was up from 924,000 MWh
of energy and 547,000 t CO 2 , respectively, in 2017.
HPGR also figures in Weir Minerals’ future
mining plans, with Weir Group CEO, Jon Stanton,
recently including the technology as one energy
reduction strategy within the industry.
Meanwhile, combining an optimal drill and
blast process with ore sorting and preferential
crushing can deliver an “optimum, gangue-free
ore carrying an optimum head grade to a ball mill
circuit”, according to Moly-Cop’s Head of
Innovation, Dr Paul Shelley.
Before companies immediately look to invest
in new comminution technologies to bring down
their energy consumption, Özer said they might
want to ensure their current equipment is
performing as it should.
“Inappropriate feed and/or grinding media
size, less than optimal circuit operating
parameters, bad classification efficiency, and
under-utilisation of comminution equipment due
to insufficient planning and poor execution of
planned maintenance” were some of the
common issues he identified.
There were also opportunities to address
trickle-fed cone crushers, which decreased the
life of wear parts and product quality; incorrect
mill speeds, resulting in increased grinding
media consumption and premature wear or
breakage of mill liners; and an imbalanced split