Fortescue’s recently deployed electric excavator has reached the milestone of one million tonnes moved since it became operational. Over the past three months, the excavator had been running at partial capacity while the site team familiarized itself with the new piece of equipment.

Now operating at full-speed, its performance continues to steadily improve with the excavator at times performing better than its diesel equivalent. The team’s focus is now on ensuring its consistent performance.

This is such an exciting milestone for Fortescue and our decarbonization journey. Importantly, we’ve been able to achieve this while maintaining our high safety standards.

We will have two additional electric excavators commissioned by the end of April. Once we decarbonize our entire fleet, around 95 million liters of diesel will be removed from our operations every year, or more than a quarter of a million tonnes of carbon dioxide equivalent.

—Fortescue Metals CEO, Dino Otranto

Located at Fortescue’s Chichester operations, the Liebherr R 9400 E excavator currently operates partially off solar and is powered by a 6.6kV substation and more than two kilometers of high voltage trailing cable.

The R 9400 E is a repowered diesel-drive R 9400. Liebherr said because it takes a modular approach to building its larger mining equipment, repowering a diesel-drive excavator such as the R 9400 can be completed in a matter of weeks.

Approximately 60% of an electric-powered Liebherr mining excavator is the same as a diesel-driven machine, which helps to simplify the repowering process.

—Chris Di-Nardo, Project Manager, New Machine Deliveries, Liebherr-Australia Pty. Ltd.

Among the changes necessary for the R 9400 to become an R 9400 E, the diesel powerpack and fuel tank needed to be removed and replaced with their electric counterparts—in this case, an electric-drive powerpack and a high voltage electric cabinet respectively. Components needed in the diesel-drive R 9400—such as the water-cooling radiators, fans, exhaust, and air intake systems—were made redundant with the introduction of the electric-drive powerpack.

However, the rotary connection was a unique case. In order to accommodate the high voltage interface between the upper- and undercarriage of the R 9400 E, an entirely new rotary connection needed to be installed.

The R 9400 E requires 6,600 volts at 50 hertz for its power up process and then the electric motor and hydraulics can be started and run up. To minimize the inrush current needed to start the electric motor, Liebherr developed a specialized system that consists of high voltage transformers. This system of transformers reduces the current required from the customer’s power grid to avoid excessive network disturbance.

Fortescue’s intention is that all electrified mining equipment will eventually be 100 per cent powered by renewable electricity.

The milestone comes just days after Fortescue’s 240-tonne battery electric haul truck prototype, Roadrunner, reached its own milestone during its onsite testing.

Roadrunner recently completed its first phase of testing which exceeded the performance expectations of the battery power system. This included laps around our testing track and ramp tests with hill starts, all while carrying 231 tonnes of iron ore.

—Dino Otranto