COMMINUTION & CRUSHING
also felt the pressure to come up with more
environmentally friendly equipment, responding
with ambitious programs of their own to tackle
climate change.
FLSmidth, in November, launched its new
MissionZero sustainability program at its Capital
Markets Day aimed at significantly reducing
emissions across the global cement and mining
industries by 2030, while Metso recently had its
greenhouse gas (GHG) emission targets approved
by the Science Based Targets initiative (SBTi).
These targets include reducing Scope 1 and 2 GHG
emissions by 25% by 2030 and cutting transport
emissions by 20% by 2025.
Outotec’s own targets – reducing the absolute
Scope 1 and 2 greenhouse gas emissions of its
own operations by 13% as well as Scope 3
emissions by 10% by 2025, compared with its
2017 base year – were validated by the SBTi in
early 2019.
These initiatives come on top of Weir Group, the
parent company of Weir Minerals, launching a
sustainability strategy that would enable net zero
carbon dioxide emissions in mining through
supporting the industry’s technology
transformation and halving its own CO 2 emissions
by 2030.
The likes of Rio Tinto, BHP, Anglo American and
others have also made significant commitments to
investors to cut their GHG footprints.
Leading from the front
While these mining companies are clearly
prioritising their environmental, social and
governance initiatives when evaluating their
operations, this philosophy is not evident across
the entire sector.
When asked whether he had seen energy
efficiency move up the list of priorities for mining
companies assessing their comminution
requirements, Alan Boylston, Director, Process
Engineering Development, at Metso, said: “It
depends. It’s not necessarily just about the
orebody, it is about the owner too.”
Speaking to IM on the side lines of the recent
SME MineXchange Expo and Conference, in
Phoenix, Arizona, he continued: “If we’re talking
about an owner that has access to a lot of capital –
the majors or a mining company with government
backing – then that focus is a real thing.
“Often, however, increased energy efficiency
and capital costs are at odds with each other. If
you are a mid-cap or junior miner and you are
faced with the prospect of having to pay so many
million more to put in this energy efficient
equipment, they quite often say, ‘that would be
nice, but we don’t have the money right now’.”
Boylston says there are cases where, if mining
companies approach the OEM early enough in the
design phase, it can design scenarios where the
capital cost is comparable or even less for an
12 International Mining | APRIL 2020
thyssenkrupp installed 12 HPGRs and
10 large ball mills at Freeport
McMoRan’s Cerro Verde mine
energy-efficient design than a conventional
flowsheet but, again, it depends on the project in
question.
“One example we’ve looked at recently is a
large mine site where they were going to go with a
HPGR to ball mill type design, except that the ball
mills were going to be large enough to require
gearless motor drives – which can be very
expensive,” Boylston said.
“In this particular case, we suggested an HPGR,
to a ball mill, to a Vertimill; so a third grinding
stage. This allowed us to go with a smaller ball
mill with dual pinion drives and then finish up the
grinding in a more efficient Vertimill – reducing
your energy and media consumption substantially.
So, there were opex benefits to the energy
efficient design and the capex – as you were
getting rid of the GMDs – was comparable with the
original design.”
Such examples prove illustrative for mining
companies on the lookout for energy efficient
comminution options, but Boylston believes the
take up of such technology would benefit from
wider industry acknowledgement of the potential
carbon footprint improvements they offer.
“With, for example, a Vertimill, when you are
talking about tertiary grind or re-grind
applications, these machines are much more
efficient than ball mills in the range of 30-50%
when it comes to power, which is directly related
to greenhouse gases,” he said.
Vertimills also use a lot less media – in the
order of about half the media a ball mill does,
according to Boylston. “That is intrinsic, or
embedded, CO 2 from having to make that steel
media and transport it to site.
“When you start adding all of those things
together, if greenhouse gas load or carbon
footprint is something that starts to become
tradeable, all of these technologies that on the
surface add a little bit of capital cost can be paid
back with real dollar savings in media and power,
and also the credits from any greenhouse gas
abatements.”
Should such a situation arise, certain
‘alternative’ technologies are in line for extra
credit.
Learning from other industries
More than three decades have passed since the
introduction of HPGRs, yet this crushing tool is
still to achieve the widespread adoption many
assumed would occur upon its release.
Originally implemented in the cement industry
in 1985, it later found a home in the circuits of
diamond and iron ore operations. It took until
2006 for a HPGR to be installed in a copper
processing circuit – the Freeport McMoRan-owned
Cerro Verde mine, in Peru – and has taken even
longer to filter down to precious metals mining.
As recently as September 2019, Coeur Mining
told investors during a site visit, “HPGR
technology is relatively new to precious metals
mining, although it has been proven in processing
other materials”.
In reviewing a newly commissioned
comminution circuit at the Rochester mine, in
Nevada, USA – a thyssenkrupp Industrial
Solutions HPGR – the company said it expected a
boost in both silver recoveries and lower operating
costs by applying the technology at the mine.
The precious metals miner’s HPGR order comes
on top of an unnamed Middle East gold mine
selecting Weir Minerals’ Enduron ® HPGR for its
own asset. Weir claimed the HPGR could provide
the operation with a potential energy saving of
22% and a more than 25% increase in throughput.
And, close by in Turkey, Eldorado Gold recently
said it will replace the tertiary crushing circuit at
its Kisladag mine with a HPGR circuit as it looks to
extend the mine life and improve gold recoveries
at the heap leach operation.