MIRS adapted the design of a robotic arm, common in industrial manufacturing, to the mining industry to replace individual trommel panels. Courtesy of MIRS

A trommel is one of the key components of a SAG mill, but it is a difficult and dangerous piece of equipment to repair. Made up of a series of heavy duty rubber screens, the trommel sorts and sieves the milled ore before it exits the mill. If the panels are damaged and not replaced, the holes risk becoming too big and allowing oversize ore to make its way into later stages of processing and damage the plant.

So whenever there was a maintenance shutdown at BHP’s Escondida mine in northern Chile to replace SAG mill liners, the mill’s trommel panels would also have to be replaced. It was difficult to get those panels changed out in the scheduled shutdown time and the work was unsafe. The process required two workers to enter the trommel with prybars and sledgehammers to whack, pry and jostle the individual panels out. Then the new panels needed to be whacked, pried and jostled back in place. The work was so dangerous a fatality occurred in October 2016, according to BHP.

The major miner needed to find a solution but it was not sure if it would be able to develop a solution in-house, according to the company’s head of commercial innovation for the Americas, Susan Lasecki.

“In mining, we’ve been doing pretty much the same thing for the last hundred years. But as we look around us, industries are being disrupted,” Lasecki said. “We believe that we have a choice, we can continue to do what we’re doing and wait for somebody to disrupt us or we can disrupt ourselves and create our own future at BHP…We’d rather be in control of our own destiny.”

BHP decided to turn to its supply innovation program, which began as a way to farm out some of the challenges the company was facing to outside firms, instead of having someone on staff to solve each and every problem.

“We put our business challenges out to the market and they become a fuel to create an ecosystem of entrepreneurial innovation in the community and the countries where we operate,” Lasecki said. “What that delivers is innovation back into our company, but also the creation of entrepreneurial innovation that creates companies and jobs beyond us.”

Faster and safer

In 2013 BHP awarded the project to MIRS, a Chilean company that engineers and constructs industrial robotic solutions for various applications. To solve the problem and get workers out of harm’s way, MIRS took the idea of a robotic arm, common in industrial manufacturing, and developed a series of tools and sensors for the head that could identify, extract, clean, and replace individual trommel panels.

“It’s a system that is a bit unique to us…it wasn’t as though we had a solution on the shelf and just sort of had to adapt it,” said MIRS vice-president Tom Gabardi. “Like so many of our solutions, this was another one where we had to do the basic engineering and conceptual design and think this thing through from the get-go.”

Once an operator orients the arm within the trommel, the robot is able to run fully automated for most of the operation. (For one section of the trommel, it requires the assistance of an operator).

MIRS developed a series of tools and sensors for the head of the robotic arm that could identify, extract, clean and replace trommel panels. Courtesy of MIRS

Using its cameras and sensors, it is able to identify which of the four different types of panel it is pulling out and work its way through them as a series. Once it has identified the panel to remove, it first cleans the area with a high-pressure water attachment, then removes the panel and cleans the newly exposed area. The robotic arm then picks up the new panel, lubricates it, and puts it into place.

Not only does the arm keep workers out of the dangerous environment inside the trommel, but it is also much faster, Lasecki said. “Manually the process took 24 hours as a baseline, and the robot is able to do it in eight hours,” she said. “So that’s 16 hours of downtime saved.”

Because of the complexity of the project, testing a prototype in the lab was not going to be good enough. For this trommel arm project, MIRS was able to go to the company that produced the mill, FLSmidth, and test the robot on a trommel that had seen actual use. Gabardi said being able to test the robot that way made a huge difference to developing the solution.

“Our system that we’ll build in our laboratory performs extraction and replacement tasks with relative ease, but the challenges increase when working on a trommel that has actual mud. Those panels are really hardened,” Gabardi said. “It’s very different than use in a kind of a simulated lab environment. Now you’re actually removing panels, and you’re dealing with a system as it really is in the plant.

“[It] really helped us with the development both in terms of giving us as much time and access as we needed to do it, and also not to provide any disruption to their regular operation,” he said.

Creating room for the future

Lasecki said the mining industry is not always on the bleeding edge of innovation, and through BHP’s supply innovation, the company wants to keep itself from being disrupted.

“[The mining industry knows] that innovation would help us to be productive, but we’re not willing to take the risk to bring the innovation in,” she said. “So, what supply innovation does, through putting the challenge now to the market and bringing them back in, is we start in small, incremental bites to get the operations used to accepting risk, able to see the success, and therefore ready for the bigger changes we know are to come.”

The trommel arm is one of the early fruits of the program, Lasecki said. “We’ve actually really improved our methodology of doing this to deliver more successes going forward in the last year and a half, and now we have a portfolio of various different stages of about 40 projects.”

In one light, the addition of robotics to an industrial site is not the most future-forward application, but in a large and sometimes lethargic industry, it makes for a big leap.

“If you look at it in a pure way, this is a robotic arm that was used in the automotive industry,” Lasecki said. “And so the robotic arm itself is not that innovative. It existed and automotive was using it, but from a mining industry perspective, it’s something that we’ve never done before. We never had a robot like that on site.”