A recently published article from the Electric Mine Consortium (EMC) was titled: Examining the alternate pathways to decarbonising fleet in an underground mine. The author, Michelle Keegan, EMC Manager, stated: “We’re now seeing OEMs who once thought BEVs were the only path, investing in hybrid vehicles. Miners are starting to trial diesel-electric and hybrid loaders, with significant improvements over diesel alternates, while others are looking more closely at trolleys as a result.”
The cited reason – a realisation “that the current charging technology, charging infrastructure and the number of battery swap-outs required to make it up a typical decline will impact productivity, and our desired solution could be up to five years away. We’re still learning about battery technology, our management of risk around it and the real productivity impacts with charging.”
She adds: “Driven by technology available today, hybrid solutions in heavy haul appear to offer a transition technology that will enable lower emissions onsite now, while waiting for technology ready electric solutions . Without requiring additional charge infrastructure, hybrids offer lower emissions, with improved fuel efficiency and productivity. Adoption of this technology can be implemented with limited operational impacts.”
While there is some truth in this – there is also no doubt that the pace of orders for full battery electric equipment from Sandvik and Epiroc in particular, including whole fleets, is rapidly increasing. Caterpillar only this week showed off the 45-t class battery underground truck prototype that will match with its all electric R1700 XE LHD.
That said, some movements in the market and by the key OEMs in 2022-2023 do also reflect a parallel demand for hybrid and diesel-electric machines. To give a few examples – Epiroc in November 2022 announced a MoU with Gold Fields Australia to partner on the development of the next generation of electric drive hybrid underground mine trucks. The companies will work in a formal partnership to develop and test a proof of concept for the 65 t class Minetruck MT65 E-Drive with the aim of having a prototype at Gold Fields’ Granny Smith Mine site in Western Australia at the beginning of 2024.
Then a year later in November 2023, Epiroc announced a MoU with Byrnecut, one of the world’s largest underground mining contractors, to partner on the development of the next generation of electric drive underground loaders. The companies will work together in partnership to develop and test a proof of concept for the large underground loader segment with the aim of having a diesel-electric prototype at a Byrnecut site in Australia.
Similarly in May 2023, Sandvik Mining and Rock Solutions said it was expanding its technology portfolio by developing a diesel-electric range of underground loaders and trucks to complement its battery-electric vehicle offering. “We see the future of underground mining as a combination of multiple coexisting technologies, with different solutions for varying customer needs,” Jari Söderlund, Product Management Director, Division Load and Haul at Sandvik, said. “An immediate switch from diesel to battery-electric is not a feasible solution for every mine and application. Diesel-electric is another technology that can help our customers achieve their productivity and sustainability goals.”
Caterpillar has had success so far with its large electric drive R2900 XE – four units were intially tested in Australia by EMC members. Gold Fields then opted to invest in three Caterpillar R2900 XE diesel-electric loaders for its underground mines in Western Australia. Westgold Resources took delivery of the first commercial R2900 XE at its Midwest operations in Western Australia, as part of an agreement with WesTrac. The mining company has since agreed to purchase another six of the diesel-electric vehicles. And one of three R2900 XEs has already been delivered to MMG’s Rosebery operation in Tasmania, as well.
Last but not least there is another major player in the room – arguably with the hybrid solution that has been around the longest and has the most real mine hybrid experience. That is Komatsu Mining with its WX18H and WH22H loaders – 18 t and 22 t class respectively, formerly referred to as the Joy 18HD and 22HD.
Their stand out innovation is a Kinetic Energy Storage System (KESS). During propulsion, diesel energy is converted to electricity. Energy flows from the motors and is stored in the KESS unit. During acceleration, both the diesel engine and the energy stored in the KESS can provide the equivalent of one 400 hp engine being boosted by another 550 hp engine. Using this KESS hybrid technology, these LHDs, Komatsu says, consume up to 30% less fuel than diesel machines. This hybrid technology can therefore reduce the need for ventilation. The Switched Reluctance (SR) hybrid drive system in the WX18H and WX22H LHDs also has fewer operating mechanical parts subject to wear and tear.
Another plus point for the machines as highlighted in a review of the 22HD by Mining Plus back in 2018 is their use of ball joints on the main rotation points including the centre hitch, main boom lift pivots, lift ram lower ends and the swing axle joints. This offers an advantage over pin and bush arrangements with a much larger bearing surface and ease of replacement of the wearing surfaces.
Notably the machines have been put through their paces in a number of trials – but arguably some of these were ahead of their time. The Joy 22HD and 18HD were launched way back in 2016 at MINExpo in Las Vegas, but the true commercial demand is only really kicking in now. Initially, the 18HD was trialled at Newcrest’s Cadia East operation, while the 18HD has also seen long-term trials at Codelco’s El Teniente copper mine in Chile from 2018 onwards. Byrnecut also trialled two 22HDs, including at OZ Minerals’ (now BHP) Prominent Hill copper-gold-silver mine in South Australia, plus the 22HD has also been the subject of a trial by Gold Fields.
IM spoke to Ryan Karns, Product Director for Hard Rock LHDs and Trucks at Komatsu, about the machines: “Our recent hybrid LHD trials of the Komatsu WX18H and WX22H continue to help us build a pathway to achieve reduced emissions and increased performance for our customers. With the support and feedback collected from OZ Minerals during the two trials, we implemented platform updates to optimise the drive system’s characterisation and improve operator comfort and visibility.”
He adds: “We recently completed our last trial of the WX18H at Codelco’s El Teniente mine. The LHD met or exceeded many of Codelco’s KPI targets set out at the start of the trial. Exceptional support by El Teniente operations assisted with further advancements in the platform to strengthen its position as a breakthrough within the industry.”
Karns added that operators involved in the trials told Komatsu that the tractive effort in the new machines is incomparable with a standard mechanical drivetrain, and the addition of Komatsu’s KESS accelerates the LHD like no other. Fuel savings achieved were also a highlight of the trials, averaging 30%-plus. “We’ve seen the highest benefit in block caving and similar applications that involve longer, more consistent hauls where maximum speed is reached on a more frequent basis. As the units are now formally commercialised, we are focused on collaborating with key customers in these types of applications to maximise the value of the machine.”
