Since they were first introduced in the 1970s, electric LHDs (Load, Haul and Dump) have gained a reputation for high productivity, low total cost and a lighter environmental impact compared with traditional diesel machines. Sandvik is the global market leader in the field of electric loaders. The company is currently upgrading its electric LHD fleet with a focus on reliability, safety and operator comfort, and it will introduce a new model this year. One prototype is being tested in Finland and one is currently operating at the Northparkes copper mine in Australia. The new LH514E carries an arrowhead design bucket with a capacity of 14 tonnes. The new model is equipped with a 400-metre-long cable allowing an operating range of up to 800 metres.

“Overall user feedback on the new generation of LHDs has been positive, and mining companies are breaking production records with new Sandvik LHDs,” says Tomi Pikala, manager of marketing support at Sandvik Mining and Construction in Turku, Finland. “Now we have bundled the same record-breaking technology into a ‘green package’ to let our customers choose pure power.”

One early adopter of the electric loading machines was the LKAB Kiruna iron ore mine in northern Sweden. So far this year the mine has connected two new LH625E loaders to its power supply boxes.

Loading operations manager Lennart Stålnacke, who has worked at the mine since 1989, says electric LHDs have been running in the tunnels for as long as he has been there.

“In 1985 LKAB Kiruna first tried out an electric LHD, the Sandvik prototype for the Toro 500 model. In the late 1980s the mine decided to switch to electric-powered machines to improve the working environment,” Stålnacke says.

LKAB started extracting ore in northern Sweden at the end of the 19th century, and in 1900 the town of Kiruna was founded atop the mine. The town was well planned for the arctic climate, with a location that made for higher temperatures than the surroundings and streets that followed the terrain to reduce the strength of the cold winds. Some 1,300 meters below the town is another well-planned layout of tunnels and shafts. But here in the LKAB Kiruna mine, the tunnels have been cut out and adapted for the company’s fleet of electric loaders. Since the decision to switch to electric machines, LKAB Kiruna has steadily replaced its diesel-powered machines. Today the mine has 17 electric LHDs and three diesel-powered loaders. The electric LHDs are used for production loading, carrying an average of 25 tonnes in the bucket.

“Our 25-tonne machines are among the largest in underground use in the world. When the bucket is full it can carry as much as 30 to 35 tonnes. By comparison, the largest diesel-powered machine in our fleet carries a bucket weight of 21 tonnes.”

The sound of 30 tonnes of rock being dumped into the ore pass is always impressive. In the high-tech government-owned LKAB mine, however, the working environment has gradually improved since the switch to electrical machinery and equipment. There’s less noise, fewer vibrations and no emissions. Further advantages include less heat and superior fire safety due to the absence of flammable fuel, exhaust or hot engine parts. Besides creating a better working environment in the mine, electric LHDs are better for the global climate.

Electricity is the most environmentally friendly power source due to its high efficiency. If the electricity is produced by renewable sources, it adds to the electric LHDs’ climate-friendly advantage over their diesel-powered relatives, especially since electric motors produce less waste due to the reduced need for oil and filter changes, repairs and rebuilds.

The layout of the LKAB Kiruna mine’s tunnels and shafts has been adjusted for the loaders and their cables. Still, the fleet includes three diesel loaders. “When a new excavation area is opened, diesel loaders are more effective since they have greater flexibility and can be moved around faster. Once the space turns into a production area, the electric LHDs are brought in so that they can be ‘pumping iron’ day in and day out, without having to stop because of high emissions. When the area is almost emptied, the diesel loader is brought back in for a final shift of loading.”

What the electric LHDs lack in flexibility they gain in efficiency. Once in place, the electric loaders are more effective than their diesel-powered colleagues. Furthermore, their capacity has increased over the last five years, Stålnacke says. The electric LHDs now average 500 tonnes an hour. In general, Stålnacke has noticed that more and more mining companies are discussing the advantages of electric machines.

“Diesel is expensive, and eliminating emissions improves the mine’s environment and working conditions. Also, the deeper you dig, the harder it becomes to ventilate the mine.”