Breathing easier underground

A new electric vehicle is a breath of fresh air for workers at the Atacocha mine in central Peru.

Buried in the heart of the Andes Mountains, the Atacocha mine winds down through the Earth, chasing veins rich in zinc, lead and silver. Eighty years since the first tunnel was dug out, the mine now extends more than a kilometer down into the mountain.

March 28, 2019. Installations of the Atacocha mine, operated by the company Nexa, where the Scooptram ST7 Battery of Epiroc is used in underground mining works. Photo: Juan Carlos Recabal / Mining and Construction / Epiroc

Just as management prepared to build a new communication tunnel to improve access to the mine’s production levels, Epiroc offered Nexa the Scooptram ST7 Battery, a battery-electric loader.

Equipment and personnel previously had to climb to over 4 000 meters to reach the main entrance and then descend the seven-kilometer ramp down through the ground to reach their places of work, a journey that could take up to an hour.
The new tunnel, which was situated 700 meters lower, reduced travel time to just thirty minutes.
Excavating the 2.2-kilometer-long tunnel with only one access represented a major challenge in terms of maintaining air quality.

The powerful machines used for drilling, lifting and hauling rock out of the mine release a toxic mix of carbon monoxide, nitrogen oxide and fine dust that can negatively affect the workers’ health.

Nexa customer story

“The diesel motor is quite dirty, and the amount of smoke it generates sometimes prevents us from working,” says Yordan Rojas, a fourteen-year veteran of Atacocha.

In most of the mine, a huge ventilation system ensures a continuous airflow that disperses the dirty air. But in closed tunnels, the contaminants can quickly accumulate, exposing workers to health hazards.

In such conditions, operators work inside hermetically-sealed cabins, while other workers must wait thirty minutes or more for the gases to disperse before they can enter the work zone safely.
Battery-electric motors do not give off any emissions. So, they do not present the same challenges as their diesel equivalents when it comes to working in closed conditions.
The timing of Epiroc’s offer could therefore not have been better.
“It was the perfect fit for the needs we had at the time,” recalls Ludwing Esteban, Atacocha‘s maintenance manager.

Nexa customer story

Since it arrived on site in January 2018, the electric vehicle has been a big hit with management and the operators, who fight to drive it.

“I have never seen a machine like this…there is no pollution, no gases,” says Rojas. “It is more comfortable for the operator and everyone else there.”

The Scooptram ST7 Battery has also proved itself a match for its diesel-driven cousin, pushing and lifting tons of rocks with ease. A longer boom enables it to load haulage trucks without the need for a platform.

There are other advantages to using electric vehicles.
Unlike a combustion engine, the electric motor hardly makes any noise as it drives through the mine’s muddy tunnels, reducing the strain on miners’ eardrums.

Nor does it off large quantities of heat, an advantage when temperatures underground can reach a sticky thirty degrees Celsius.

The one drawback has been that, unlike a tankful of diesel, the Scooptram ST7 Battery’s large battery does not last a whole 12-hour shift and must be changed after four to five hours of use.

But changing the battery has proved surprisingly easy. After training by Epiroc’s onsite technician, Rojas and his colleagues can now change the battery in just 15 minutes or so. And no fuels and lubricants mean lower operating costs and fewer tanker trucks making the perilous journey to the mine.

Charged from Nexa’s own hydroelectric plant, the Scooptram ST Battery is also helping to reduce the company’s carbon footprint.

With so many clear advantages, it is no wonder that the world’s mining industry is clamoring to electrify its mine fleet as soon as possible.

Esteban explains that Nexa would like to electrify its whole mine fleet within five years.

Excavation souterraine de roches 2019 Témoignage client International Les chargeuses électriques