VA Erzberg with the help of Liebherr has been testing a trolley-assist system for its T 236 diesel-electric haul trucks at its iron ore mine, located near Eisenerz, Austria. Originally, a truck was modified to operate with an overhead line connected through a current collector on a 500-meter-long test track. At the end of September, the trolley line was extended to 5 km. The company estimates that it burns 4.5 million liters per year to transport more than 13 million metric tons per year (mt/y) of rock. That figure could be reduced by 3 million liters if the new trolley systems perform as planned.

The current collector’s bars connect the truck’s drive system to the overhead power lines on the uphill haulage segment. This arrangement, which differs from conventional pantograph systems, allows for tracks with smaller radii and even switchbacks. It also allows for a wider use of the haul road width aside of the catenary line in comparison with conventional pantograph solutions. This becomes important when haul road conditions are less than ideal due to weather conditions.

“There are only a few companies in the world that use overhead line technology for their trucks,” VA Erzberg Technical Director Josef Pappenreiter said. “However, we realized very quickly that the existing technology would not work for us.

“Our newly developed technology is different from everything previously available on the market in terms of both the overhead line system and the vehicle technology itself. This could only be developed with our cooperative and innovative partner Liebherr Mining in Colmar.”

VA Erzberg will be observing how the weather conditions will affect the overhead lines and the performance of its six 100-mt T 236 haul trucks on the 5-km track during the winter in the Eisenerz Alps. “Another challenge is the entire electrical engineering as all six T 236 could be connected to the overhead lines simultaneously in several places,” said Peter Schimek, project manager for VA Erzberg.

When connected to the overhead power lines in trolley mode, the full power capacity of the electric wheel motors of the T 236 can be translated into speed on grade while the diesel engine idles, reducing fuel consumption and emissions.

For the long term, VA Erzberg said it expects to save around 3 million liters of diesel and eliminate 4,200 mt of CO2 emissions. Furthermore, the emission of nitrogen oxides and fine dust will also be reduced.

“With this technology, we expect a sustainable energy-optimized production,” Pappenreiter said. “Around 13 million my/ of rock are currently transported in the mine. The cost factor for ore production is correspondingly high. In addition to the positive environmental effects, an investment in this new technology also secures the sustainable extraction of iron ore for domestic steel production.”

He added that around EUR20 million ($23.5 million) will be invested in the project.