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Underground air support

Drone deployments at the Hoyle Pond mine provide a more precise picture of underground operations

By Kelsey Rolfe

Nov 6, 2019
SafeSight’s open-platform product gives surveying teams full control of how the drones behave underground.
 
The surveying team at Newmont Goldcorp Porcupine’s Hoyle Pond mine was having trouble getting a clear picture of its narrow vein deposits using the conventional laser survey method on its stopes. So they called in air support.

Since May 2018, the mine has been working with SafeSight Exploration, a drone company specializing in mining sector applications, to use its drones for underground surveying work. The goal of the pilot was for Newmont Goldcorp Porcupine to be able to do full scans of Hoyle Pond’s stopes to improve its reconciliation processes and engineering designs, fine tune its block models and reduce the dilution of its recovered ore.

“The true, all-inclusive cavity scan that SafeSight offered had the potential to help us understand how we could control dilution,” said Paul Lévesque, continuous improvement superintendent at Porcupine. “With that carrot in mind, we started going down that road of working with SafeSight.”

Part of the Porcupine gold district near Timmins, Ontario, Hoyle Pond is mined using the narrow vein longhole method. Because Hoyle Pond’s veins move laterally from level to level, Lévesque said it can create “shadows” when the mine’s surveying team does laser surveys of its stopes, preventing them from getting a clear picture. “The only way to get a full scan of the entire stope is to have a scan that’s mobile,” he said.

Using drones for surveying and other functions is common in open-pit mines but is relatively new to the underground. When some of Lévesque’s colleagues from what was then Goldcorp met SafeSight at the CIM Convention in 2018, they recognized the technology’s potential for Hoyle Pond. Soon after, Mike Campigotto, SafeSight’s president, and his team were on site in Timmins.

Test flights

SafeSight was founded more than two and a half years ago by a group of engineers from various disciplines. And while the company had a surveying drone when the team went to Hoyle, Campigotto said it was still a work in progress.

When SafeSight got started, Campigotto said, the team spent eight months “immersing ourselves in all things underground.” The company built a drone that incorporated light detection and ranging (LIDAR), high-definition and 360-degree photography, video, LED lighting and radio frequency control systems, and targeted it to underground mining applications.

The company tested its drone at NORCAT’s Underground Centre test mine “to understand the parameters of underground work,” Campigotto said, “and based on that experience and training, we refined the look and feel and functionality of the [drone] underground.” With an updated model, the company did “about a dozen” more test flights at underground mines in northern Ontario.

Lévesque’s invitation to come to Hoyle Pond came at exactly the right moment, Campigotto said. “We’d done as much as we could with field testing and lab development, but to create a rugged repeatable solution that worked in practice we needed a willing partner.”

But before SafeSight’s drones could soar, they hit some turbulence – or, more precisely, underground air pressure. While the company had done extensive underground work, Hoyle Pond was deeper than its other test sites, and the air pressure prevented the drone from flying. Drones use barometers to understand where they are, and going underground muddies the reading. “The drone [couldn’t] understand it was underground and it wouldn’t fly,” Campigotto said. “We were one pressure point past the limit and surprisingly couldn’t arm the drone.”

SafeSight ended up switching out the drone’s off-the-shelf flight controller with one that was open platform. “With stock flight controllers,…they will give you software development kits but not let you into the brain of the unit,” said Campigotto. “We moved to an open-platform product that gives us full control to get the drone to think and behave in any way we want.”

SafeSight also customized its drones to match what the Hoyle Pond team wanted, Lévesque said. After some of the early flights, the surveying team found the 360-degree camera useful but wanted to be able to transform its footage into a 3D point cloud. “Mike’s team designed brackets for different cameras, and now we’re capable of flying different drones for different applications – video or LIDAR or video that will transform to get a 3D point cloud,” he said.

SafeSight now has two drones, the heavier-duty DB2 surveying drone, which is equipped with LIDAR, 360-degree photography and video, and a lighter model, SafeScout, which has a Garmin 360-degree camera for pre-surveying review of the terrain. Newmont Goldcorp now has one of each in use at Hoyle Pond, and a few additional smaller drones that are used to train surveyors.

Taking off

On the 1500 level at Hoyle Pond, miners had previously stopped mucking and backfilled a stope because the brow was failing – all the while knowing they had left ore behind. “We couldn’t safely fully assess the area by walking into it, but what we could do is fly the drone and have a look [to assess] the stability of the drift behind the area,” Lévesque said.

The survey helped them determine how to safely get in to reach the remaining ore and netted 4,500 tonnes of ore at 14.4 grams per tonne gold.

In addition to achieving their initial goals of better stope surveying, Newmont Goldcorp Porcupine has seen other benefits. The data the company receives from the drones has “accelerated our decision-making process” on things such as where to muck next and whether areas previously deemed dangerous can be accessed or rehabilitated, Lévesque said. “We’re able to make decisions on information we never would have had before.”

In another area of the mine that had previously experienced a few ground failures, and was deemed too unsafe for workers to inspect, Lévesque’s team sent in the scout drone to get video of the area, and then sent in the DB2 to map the area with LIDAR. “We were able to make decisions on the rehabilitation of the area based on the survey data and video data,” he said. “We’ve rehabilitated areas where we probably would have bypassed in the past, knowing we could do it safely, knowing the exact failure mechanisms.”
 
A video image from a SafeSight drone.

The drones have also increased the amount of surveying the Hoyle Pond team can do and shortened the time it takes to process the resulting data. Using the conventional laser survey method, the team could do one cavity survey a day, which would take between 45 minutes and an hour. Now, while the nature of the site makes it difficult to do a flight every week that would survey all of the underground workings, the team does an average of two flights a day that target specific stopes or areas of the site. “We do see most of the stopes,” Lévesque said. The drone survey, from setting up to clearing out, takes 20 or 25 minutes, and the flight itself is usually between three to five minutes.

“We get all the data, and better-quality data, in a more complete set than we could in 45 minutes to one hour,” Lévesque said.

The team is also able to process the data quickly on site. Normally, the point cloud that comes from a laser survey can take days to trim down to be usable on the computer. The DB2 drone does it automatically. Once the point cloud data has been pared down, it can be exported from the drone onto a USB.

“That’s great for us. I don’t think anyone else [in the industry] processes this type of data on site,” Lévesque said.

Co-pilots

Campigotto said the project’s success wouldn’t have been possible without Newmont Goldcorp Porcupine’s willingness to let the drone company learn and improve its technology. “[They were] understanding of the adaptation that’s required to get the program to work,” he said. “I would caution any site that feels they can buy a drone off a supplier, have a couple of weeks of training. To get the benefits…you really need to work in lock-step [with your supplier].”

Lévesque, for his part, said Newmont Goldcorp Porcupine was not bothered by the work involved because it saw the potential in the technology and appreciated SafeSight’s ability to solve the problems that cropped up. “When you collaborate and bring something new, you need to expect that not everything is going to work out the first time,” he said. “You don’t have to have a solution right now, but you need to have a path forward.”

SafeSight and Newmont Goldcorp Porcupine are continuing to develop the drone program. Stage one, which rolled out over the summer, was a pilot-assistance mode that allows for some autonomy but still requires the pilot to interact with the drone. The next stage, which is expected to be ready in the fall, will be a direction mode that gives the pilot the ability to set a flight path for the drone and monitor its performance.

And the third phase? Fully autonomous operation by early 2020. “It’s not a long development curve, but we don’t want to develop autonomy in a lab,” Campigotto said. “We’re working operationally with [Hoyle Pond] to deploy pieces to ensure they work in the reality of daily operations.”
 
 

Source: https://www.safesightxp.com/post/underground-air-support