BATTERY AND ELECTRIC VEHICLES
Above ground developments
Thanks to Boliden’s recent trial at its Aitik open-pit mine, in Sweden, the
subject of surface mining trolley assist is back on the industry’s agenda.
Offering environmental and productivity benefits, trolley assist
technologies have been spoken of for decades. In the height of the oil crisis
of the 1970s, numerous studies examining applications were completed and
miners made preparations to reduce their reliance on diesel.
Despite this, widespread industry adoption has not occurred.
ABB, which supplies not only batteries, drives and motors for battery-
electric equipment, but can also provide the infrastructure required for
trolley assist projects, believes the market is about to turn once again.
Gunnar Hammarström, Global Product Manager Trolley Electrification
Systems for ABB, thinks there are three main reasons why it is about to take
off.
“One is the legislation and environmental part of the business case,” he
told IM.
Boliden, which has moved from the 700 m trolley line trial at Aitik to
confirming it will install an additional 3 km of trolley line at the mine, plus
1.7 km at Kevitsa (in addition to the accompanying conversion of 13 diesel-
electric haul trucks, including some of the site’s new Komatsu 830Es), says
it will reduce its diesel consumption by 5,500 cu.m/y when its investment is
complete. That is a big number.
“Another completely different reason for why demand has been picking
up, especially for larger trucks, is there are a lot of diesel-electric trucks
coming into mines,” Hammarström said. These trucks already have an
electrical system on board to tap into, which makes it easy to put them on a
trolley line.
Lastly, the volatility of fuel prices has had an impact, according to
Hammarström. This is leading miners to diversify their energy mix to help
reduce and stabilise input costs.
When added to the productivity gains that can be achieved with trolley
assisted haul trucks and the reduction in noise when trucks run on this line,
it is hardly surprising Boliden is not the only one charging into trolley assist.
In the last year-and-a-bit, First Quantum Minerals has said it will equip its
Cobre Panama copper-gold mine, in Panama, with trolley assist, while
Austria iron ore miner, VA Erzberg, has announced it intends to electrify the
main haul road of its Erzberg mine site and operate a fleet of T 236 trucks
from 2021 under trolley assist.
On top of this, RNC Minerals has said it is studying the use of trolley
assist at its Dumont nickel-cobalt project in Quebec, Canada.
While trolley assist has been used long before the mine electrification
phenomenon we know today gained traction, Hammarström sees it helping
facilitate this market move.
“Generally speaking, I think for most of the vehicles you have in a mine,
you can go on battery, but it is very far into the future where you have major
several cassette options such as a scissor lift, fuel
& lube and ANFO loader.
Timberland said: “The RAM40 was designed
with better sightlines and increased visibility
around the machine, making it safer for the
operator and everyone working near the
equipment. In addition, all maintenance activities
can be performed from ground level, allowing
easier maintenance and daily checks. A standard
carrier means common parts allowing for better
service and support, along with quicker build
times for new capital orders.”
Timberland Equipment says its new BEVs offer
a “true” battery powertrain without the need for
22 International Mining | MARCH 2020
uphill transportation of all your production in the mine through batteries,”
he said.
The technology involved with stationary charging and the ability to re-
charge the battery when going downhill would need to improve on the
biggest haul trucks to make it a viable proposition, he explained.
“Yet, if you look into the future – and not that far – a diesel electric trolley
might be an intermediate phase,” he said. “If you have invested in trolley
now, you can certainly use it when you have batteries (driving the trucks).”
This could see battery-powered haul trucks carry out tasks ‘off-line’ when
going downhill or on a flat before they ‘attach’ back onto the line for uphill
transportation of material where the battery can be recharged.
ABB is not the only company thinking trolley assist has a big future in
open-pit mining.
One of its partners on the Aitik trial, Caterpillar, has recently
commercialised its trolley assist system for Cat electric drive mining trucks.
The move should allow mining operations to reduce carbon emissions,
lower fuel and engine costs, and boost speed-on-grade for greater
productivity, it said.
The Cat trolley assist retrofit kit is currently available for the 795F AC
truck, with the trolley design compatible with three other Cat electric-drive
mining trucks, namely the 794 AC, 796 AC and 798 AC.
During the nearly two-year pilot project at Aitik, four 795F AC trucks were
used on the 700 m electric trolley line and, according to Jonas Ranggård, a
Program Manager at Boliden, availability has been high despite the arctic
conditions.
“There are few projects that can show both environmental and
productivity improvements of this magnitude,” he said. “This is why Boliden
has decided to expand the trolley infrastructure in Aitik and equip its entire
795F AC truck fleet with trolley assist systems.”
Eric Ruth, Electrical Senior Product Team Leader with Caterpillar, said:
“We feel that trolley assist can play a role in achieving mining companies’
greenhouse gas reduction goals. Simultaneously, trolley assist boosts
productivity by increasing speed-on-grade. In fact, testing at Aitik mine has
shown that a 795F AC equipped with trolley assist is the most powerful
mining truck in the world!”
The trolley system significantly reduces diesel engine emissions at the
mine via substitution of electricity during the most demanding part of the
truck work cycle. Powering a 337 t payload 795F AC via trolley on a 10%
grade as it climbs the ramp out of the pit saves up to 40 litres of diesel fuel
per kilometre of trolley line, according to Cat. Fuel and engine costs,
meanwhile, are reduced by more than 90% while the truck is on trolley.
The trolley system also boosts productivity. Operating with trolley assist,
speed-on-grade increases as much as 100% versus diesel-only mode, Cat
said. Using trolley, a loaded 795F can run at 28 km/h on a 10% physical
grade with solid haul road conditions.
mechanical components. This reduces wear on the
machine and greatly extends the amount of time
between routine service intervals, according to the
company.
Driven by design
There is clearly a plethora of electrification options
available on the market and, in the next decade,
there is likely to be even more as developments
seen underground become more prominent in
surface mining.
Yet, just as diesel-powered mining fleets are
made up of different types of machines to suit
the environment in which they operate, there will
be variety to the decarbonised fleets of the
future.
MacLean’s Marshall concluded: “It very much
depends on the geometry of the orebody; that is
what drives a lot of your decisions about how you
are going to use energy in that mine. It is based on
horizontal width and vertical height. That creates
the energy profile of how you expend energy.
“Some mine geometries will not be able to be
mined purely on battery, but there are plenty that
can.
“Each mining company will seek to work with
their OEMs to adequately design an energy and
operating strategy that works for them.” IM