When a battery-electric vehicle (BEV) caught fire underground at Glencore’s Craig Mine in Onaping last July, it was a “big eye-opener” for the company, said Steve Holmik.
“No one’s ever had to deal with an incident like this in the past,” said Holmik, a mobile equipment specialist with Glencore Sudbury Integrated Nickel Operations (SINO), who estimated this was the first reported underground BEV fire in Canada, and perhaps globally.
“We've had diesel equipment catch on fire, but we've never had a battery-electric vehicle catch on fire, so up until that stage, everything we knew about the potential of a fire with a BEV was all theoretical. We'd never had the first-hand experience of having to deal with it.”
That changed on July 6, 2020, around 10:40 p.m., while two technicians were troubleshooting solutions for a stalled BEV on the 47-4 level of Craig Mine at the company’s Onaping Depth Project.
A sudden, high-intensity electrical arcing event took place, catching the vehicle on fire and trapping the two workers behind the truck with no way to get out.
Remarkably, no one was hurt. The two workers found a compressed air line and adapted a breathing apparatus so they could access clean air while waiting for help from Mine Rescuers, who put out the fire and brought them to surface unharmed.
Even though there were no reported injuries – “not a single Band-Aid required, which was such a huge relief,” Holmik said – the company reviewed the incident with the same intensity it would have applied had it had resulted in a double fatality.
Sharing the findings from its internal investigation is one step Glencore believes will help prevent similar scenarios in the future, Holmik said.
“It's something we're not holding under a secret umbrella,” he said. “We're one of the advocates for BEVs and BEV adoption and the education of the industry.”
Holmik and colleague Craig Harris spoke to their experience during the second annual Battery Electric Vehicle Safety in Mines symposium, hosted online on Jan. 20 by Workplace Safety North.
The half-day event gave mine managers, supervisors, procurement professionals and other industry experts insight into risk mitigation efforts related to the increasing adoption of battery-electric vehicles in the mining industry.
Following the incident at Craig Mine, Glencore’s investigative team found that it was ultimately a series of missteps that led to the truck fire.
A towing incident early in the BEV’s life at Craig resulted in damage to the traction inverter.
Then, during servicing, some of the battery’s fuses were mistakenly removed and replaced with shunts, a device that allows a technician to externally power down the vehicle for maintenance.
That resulted in the vehicle being operated without overcurrent protection in place, which led to the arcing incident, creating the heat and flames that ignited the battery and caught the truck on fire.
Harris, the lead electrical engineer for Glencore’s Onaping Depth Project, said the company is now working with industry partners and vehicle manufacturers to address these problems.
First and foremost, he said, “overcurrent protection is critical.”
Much of the discussion around the batteries in BEVs has been about their chemical makeup, he noted. While that’s important, he said, more attention needs to be paid to overcurrent protection.
“Key point here is that if you don’t get this right and you end up with a situation like this (fire), you’re driving around a definite hazard,” Harris said.
A company purchasing a BEV needs to become well-versed in its system for overcurrent protection, while the OEM needs to be clear and transparent in providing that information to a client during the sale process, he said.
Harris also suggested that only authorized workers be permitted to change out fuses in the equipment, and that a component’s purpose and placement in the machinery should be clearly indicated.
Following the Craig Mine fire, for example, investigators found that the casings for the fuses and the shunts were virtually identical, making it easy to get the two mixed up.
“Our suggestion is that a fuse should look like a fuse; it should be set up in a way that only an authorized person can replace it," Harris said.
“There should also be clear labelling throughout as to what it is."
Additional suggestions from the investigative team include having technicians conduct regular basic maintenance on the machine, which includes checking that the fuses are properly installed.
Holmik noted that education about BEVs has come a long way since they were first introduced to the industry.
He’s been encouraged by the growing interest from the industry in recent years, along with advances in the development of the technology and collaboration from end users like Glencore.
“I think we've come to realize that BEVs are here to stay,” he said. “There are so many advantages with regards to BEVs over diesels, and there are some challenges as well, as we've discovered.”