Underground miners work in a unique environment. They routinely drill, blast and muck rock in the outer crust of the Earth that’s been in place for eons, untouched by humans and unaffected by most external influences. But, while doing their job, miners occasionally trigger stress reactions in that rock that can vary from merely acoustic, such as clicks and pops coming from the back or wall; to catastrophic, when massive slab failures or explosive rock bursts occur. In order to safely cope with the forces unleashed by underground excavation, miners need ground-support equipment, data and methods as up-to-the-minute as their workplace is ancient.
The machines that install the bolts, mesh and shotcrete used in today’s mines offer increased flexibility and improved performance, both of which are critical to meet the demands of modern mine production rates and labor resources. As mentioned in last month’s issue (BEVs Ramp Up Their Role in Ground Support, pp. 36–37, E&MJ, July 2022), battery electric powered vehicles also are steadily expanding their presence in underground fleets. Recent market studies suggest the pace of BEV implementation into both underground and surface mine fleets, will be governed by technological advances aimed at maximizing charging and battery capabilities to match a machine’s on-the-job duty cycle and operating range, along with capital cost and greenfield mine-design considerations.
Given the command and control advantages offered by electrically powered equipment over diesel, the next logical step in bolter, shotcrete sprayer or scaling machine development appears to be increased automation, but that may be an elusive goal: While the industry’s current emphasis is on fleet haulage and tramming equipment that can more readily be designed and adapted for driverless operations, automation progress for support machines that require an operator working from a cab or protected ground – such as bolters and sprayers – is still on the far horizon. And, for at least one major utility-machine manufacturer, automation isn’t the total answer: it’s finding out what customers want, then designing machines that offer the tools needed to meet their operational requirements.
MacLean Engineering launched its EV Series product line in 2016 and since that time, the company has built and commissioned more than 50 units in Canada, the United States and elsewhere. Collectively, MacLean’s BEVs have clocked more than 120,000 working hours underground. The Canadian company is executing a design philosophy based on connecting the mining cycle to the battery cycle through the use of appropriate battery, onboard charging and vehicle telemetry technology in BEVs that allow customers to maximize the operational benefits of a diesel-free mining environment.
E&MJ recently spoke with Steve Denomme and Jonathan Lavallee, Maclean Engineering’s product managers for bolter and shotcrete equipment, respectively, to find out how mining trends and customer desires are influencing the direction of ground-support equipment development.
Denomme pointed out that compatibility with a mine’s existing infrastructure is a major selling point for MacLean’s BEV product line. “When you have onboard charging capability as our machines do, you can plug into the existing mine infrastructure and no significant modifications are necessary. The onboard chargers handle battery charging on their own. That simplifies things and reduces ‘range anxiety’ for operators. Because our machines can work with the existing infrastructure, there’s less worry about reaching a charging point during normal operations, and downtime also offers an opportunity to charge while the machine’s being serviced.” The company also offers an option for offboard charging on its BEVs, and markets a complete line of diesel-powered bolters, scalers, boom lifts, shotcrete sprayers and mobile concrete mixers, as well.
He continued: “Our BEVs combine the convenience of onboard charging with our MacLean telemetry system for monitoring the state of the battery, providing information on battery status and performance and fault detection alerts so that we can jump on any problem quickly. Our telemetry technology is available with a variety of options; for example, safety packages that monitor how a driver is operating the vehicle; maintenance packages; or performance packages that’ll monitor bolts per hour, drill pressures.”
MacLean’s product literature describes the system as consisting of sensors and display screens installed on each unit, supported by analytics software that distills vehicle performance data based on an OEM-level of product design knowledge. The technology presents actionable data and provides prompts on in-cab screens, and also “clears away the background noise” of vehicle health telemetry by presenting data in a way that enables predictive maintenance decision making, according to the company.
“That’s becoming more important for customers because they want real-time data about machine performance, maintenance and overall productivity,” said Denomme. “The safety and maintenance packages are included as standard features on our battery powered equipment, because it’s very important to be constantly aware of the status and health of the battery.”
MacLean has steadily expanded its underground BEV product line over the past several years, introducing its first battery electric rock bolter, the 975 Omnia EV, in 2016 and the battery-powered SS5 Shotcrete Sprayer and TM3 EV Transmixer last year in a live launch event broadcast from its underground test mine site in Sudbury, Ontario. The SS5 represented a complete redesign of its flagship sprayer model, including a new carrier and ergonomically designed operator’s cab with better visibility and noise attenuation to support in-cab spraying. The sprayer also incorporates new dosing control and real-time thickness measurement technologies to improve the quality and reduce the quantity of shotcrete applied.
As Lavallee explained, “Our thickness monitoring system can be linked, for example, to mine mapping and georeferencing software, so you can essentially take imaging from the SS5 sprayer and link it up to whatever system that the mine is using for georeferencing and mapping capabilities, and get closer to a real-time image of the drifts that need to be sprayed. A geotechnical engineer can look at the information and make certain determinations, such as being able to ensure that the proper thickness has been applied and seeing exactly where remediation needs to occur, as well as monitoring shotcrete rebound to more closely determine the quantities needed to support any given drift size.”
Fully automated shotcrete machines are currently just an engineer’s dream, according to Lavallee, but they’re definitely on everyone’s future product line agenda. “There are significant challenges to achieving full or even partial automation in this area, but I think it’d be crazy to assume that’s not on every OEM’s roadmap at this point in time,” he explained. Steve Denomme agreed that the same challenges apply to bolters, but that isn’t stopping the company from moving ahead.
“We’re working right now on robotic technology to replicate what an operator does up on the deck,” he explained. “We’re running a test unit at our underground Research & Training Facility in Sudbury, to see how close we can come to getting a robot to act like the operator – with great success so far – and we’re integrating certain subsystems that we’ve been testing into a final form that we can introduce to the market when ready. This will allow mines to remove the worker from the deck, because everything the operator previously had to do will be performed by the robot. Right now, the operator will be in the cab, but with true automation we’ll be able to locate the operator anywhere and still carry out the full bolting sequence.”