Powering the World's First Fully-Automated Underground Mine

POWERING UNDERGROUND MINE

By Kate Dougherty, Energy and Mines

When the sublevel cave at Resolute Mining’s Syama Gold Mine becomes the world’s first fully-autonomous underground mine in 2019, it will leverage automated drilling, automated loading, and automated haulage. In what will be an industry first, ore from this south Mali mine will originate underground and arrive at a single pad on the surface without being manually handled.

For nearly 30 years, this West African mine has been powered by a historic, diesel-fired power station that was incrementally expanded. It currently has 28 MW of generating capacity consisting of two reconditioned 5 MW units and a series of 2 MW units. But exploring automation technology led to rethinking the mine’s power generation as well. In 2020, Syama will be powered by the largest ever off-grid hybrid power facility—a 40 MW hybrid solar, battery, and heavy fuel oil (HFO) plant.

Most of Syama’s fleet of automated mining equipment is diesel-powered, with the exception of tethered electric loaders, which will run on the power that the hybrid plant generates. While they would also like to use electric haulage, Resolute feels that the technology isn’t sufficiently advanced yet. However, John Welborn, Managing Director and CEO of Australia -headquartered Resolute Mining feels that it’s coming. “I’m personally convinced that underground mining is going both automated and it’s going electric,” he states. “The advantages in underground mining—both in removing diesel particulates and the various problems created by exhaust gases underground and the nature of ventilation—is huge, as well as having safety and productivity benefits.”

DRIVERS FOR THE SYAMA RENEWABLE ENERGY PROJECT

A number of different drivers led Resolute to choose a hybrid solar microgrid, from industry-wide concerns to local considerations.

Energy cost

Like many similar projects, finding lower-cost energy was the primary driver. The mine yields a very large-scale, double-refractory ore body that’s relatively difficult to process. Resolute has made the process of extracting the gold from the ore more efficient and has been increasingly successful with mining at Syama over the last 10 years. However, the process still requires a substantial amount of energy, and Syama has traditionally been a high-cost gold producer as a result.

Because the mine is exposed to fluctuating diesel prices, “the genesis was really recognizing that our current power costs, depending on diesel costs, ranged between 20 and 24 cents a kilowatt hour. And at Resolute we have an ambition to produce gold at a lower cost,” Welborn explains.

Logistical challenges

There’s also the significant logistical challenge of delivering diesel to a remote mine site in the south of Mali. “We have quite a strong logistical challenge in a mine that can use between 100 - 200,000 litres of diesel a day across our mining fleet and the power generating units,” Welborn says. And “it’s a long way away from either Dakar or Abidjan, which is where our fuel comes from.”

The site is located in southern Mali close to the border with Côte d’Ivoire, an area that’s still exposed to political uncertainty. Adverse weather conditions during the heavy rain season also impact the logistics of transporting equipment and fuel to the site.

Considering local communities

Resolute originally considered connecting to the West African Power Pool, a grid roughly 80 km away from the mine that sources energy from seven gas and coal-fired power stations in Côte d’Ivoire. However, “the grid-connection opportunity ultimately didn’t project to generate the savings that we had hoped, and also was politically and logistically challenged,” Welborn relates.

Building a microgrid was the most feasible option—one that’s also more environmentally responsible and provides an opportunity to supply power to local communities. “In the sort of place we’re talking about in remote West Africa, there is no greater long-term impact on health, education…[and] the local community than electrification of the community,” Welborn says.

Renewable energy options and the funding for them are increasingly available. “And there’s a couple of other exciting aspects about that,” Welborn says. One is the opportunity to develop a more sustainable, renewable, and ultimately lower-cost power solution for the mine. The other is that “instead of that traditional approach of looking to expand an infrastructure grid with power, there’s actually the remote users at the mine being the catalyst for the creation of a microgrid [that delivers power to] the local communities around the mine that we operate.”

A DUAL-TRACK PROCESS

Resolute’s process to reach a decision on power lasted roughly two years. “Internally we got a study team and we looked at a self-perform option,” Welborn explains. “But we also went out and tendered to interested parties and people who could propose to provide us with a power solution.” The company ultimately partnered with South Africa based Ignite Energy, to finance, construct, and operate the new power plant because of the ability to have the new power plant financed off-balance sheet.

“We have made an investment of more than $US200 million in the construction of the new underground mine at Syama, new equipment, the new twin declines, and new ventilation and pumping infrastructure related to that underground mine,” Welborn explains. “The ability to use an IPP model where we are not responsible or required to fund the power station—we’re just required to pay for the power it generates over a long-term off-take—is a value-creating solution for us.”

Falling prices for solar and battery storage are making the business case easier for mines. As a result, many miners are less hesitant to spend their own capital on power solutions, according to Ignite Energy’s Managing Director, Grant Berndsen. “There’s a greater willingness to explore options for outsourcing power supply through third parties and allow the mines to direct capital, their efforts, and expertise into mining.”

INTEGRATION IS KEY

The Syama plant uses freely-available, tried, and tested technologies that are currently in operation, and Ignite Energy is partnering with contractors that have rolled out these individual technologies on a number of plants over many years. However, how those technologies are brought together and interface with the mine’s requirements is crucial. Syama runs very energy-intensive equipment that needs to operate seamlessly. “Making sure you are providing seamless power and are quick to respond to the needs of the mine’s power requirements are the key,” Berndsen relates.

A number of projects where solar was tacked onto a diesel or HFO plant retrospectively have experienced problems, according to Berndsen. That type of structure “places some risk on the project, and you experience, very often, that the maximum savings aren’t realized because the hybrid controller isn’t designed and operating in an optimized fashion. So a lot of the success of the project is hinging around that integration technology.”

FUTURE INNOVATION

The rapid development and falling cost of battery storage mean that Resolute is positioned to take advantage of this development into the future. In parallel to the potential future transition of Syama to a fully-electric underground fleet, Resolute and Ignite Energy will continue to assess the advantage of incorporating large-scale and long-duration battery storage to minimise the use of fuel within the overall hybrid power plant. Whilst Resolute views fully-electric underground haulage and predominately renewable-powered hybrid power systems as yet-to-be-viable, the Syama Gold Mine is positioned to be one of the first mining operations to take advantage of this technology when it reaches maturity.

ADVICE FOR MINERS

Resolute fired the first production ring on the new Syama Underground Mine in early December, and the hybrid power plant is slated to come online towards the latter part of 2020. When that happens, Syama will be the latest case study that other mines can look to. Welborn advises miners to seek out several case studies, such as the Sandfire mine near Resolute’s headquarters in Western Australia, which built a large solar component for its energy needs, or a number of other mines in Africa that are implementing similar projects.

It’s important for miners to evaluate all of the options, according to Welborn. “Our experience running a dual-track process was evaluating our self-perform opportunities, evaluating the ability to refurbish our existing power generation, construct new power generation, and comparing and contrasting it, but also collaborating with various other external parties proposing solutions,” he shares. “My advice would be run a very clear, well-publicized study of all of the available options.”

The Syama Gold Mine is more than just another case study. The project is “special because it’s going to provide other mines and other bulk energy users in similar jurisdictions the confidence that this technology can be applied elsewhere,” Berndsen says. “Being able to promote creative, technical, and commercial structures to a customer like this will open the eyes of other customers and funders alike to what’s possible.”

Syama might enable funders to take a less conservative view on similar projects and become more comfortable with the idea of deploying renewable technology on the continent as a whole, Berndsen hopes. “Having this kind of pioneering, trailblazing-type project is extremely exciting.”