Located far up near the northern tip of Sweden is the Aitik mine, the largest open pit copper mine in the country. There, enormous Caterpillar 795F mining trucks with tires 15 feet tall haul 310 ton loads of rocks up steep inclines 24 hours a day, 365 days a year. The bottom of the mine is 1,500 feet below the surface of the earth. Combined, a fleet of 30 trucks moves 70 million tons of earth each year. From that total, 97,500 tons of copper are obtained, along with 2.9 tons of gold and 62 tons of silver.
Photo courtesy Boliden
The mining trucks are marvels of modern engineering, but they have one drawback. Each one consumes over 100 gallons an hour of diesel fuel, according to a report from TU. To address that issue, Caterpillar is converting some of the trucks to run exclusively on electric power taken from overhead wires. Batteries large enough to supply the enormous amount of power needed would simply be too large and heavy to work on individual trucks, but putting the energy needed into overhead wires solves the problem.
The overhead wiring is being constructed by ABB and Eitech, two companies with lots of experience building electrified railways and tram systems. The work is supported by a grant of $1.2 million from the Swedish Energy Agency. A similar system for trucks carrying cargo from ports to inland distribution terminals has been constructed in Southern California. The Caterpillar 795F mining trucks are already powered by diesel electric powertrains, so converting them to exclusively electric power will be fairly straightforward and Caterpillar has already started on the conversions.
Photo courtesy Boliden
Initially, the electrified trucks will only be used to haul non-ore bearing rocks to a 200 foot high area a half mile away, but if the system proves reliable and cost effective, it could be added to the road leading from the bottom of the mine. Such equipment has never been used in such harsh winter conditions before, so a “proof of concept” period of time is needed to make sure the trucks won’t break down on the way up or down, which could bring the entire mining operation to a halt.
Each truck will be capable of handling up to 4.75 megawatts of power. With that much energy on tap, they can actually move twice as fast as the diesel electric trucks in use today, which struggle to reach 10 miles per hour on the uphill climb from the bottom. Faster speeds could lead to significantly higher production from the mine, leading to more revenue for the operators.
Economics is the principle reason to make the switch to all electric power, but eliminating the emissions from 30 diesel powered trucks burning 100 gallons of diesel fuel an hour into the pristine atmosphere near the Arctic Circle is a benefit the entire world can celebrate.
Hat tip to Leif Hansen
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