Split Lokotrack crushes rocks deep down in a tunnel in Austria

A special split Lokotrack

“We actually had two simple-sounding requests for Metso. In addition to being a full electrically driven unit, it needed to be split into parts no longer than seven meters for lowering. And secondly, the constant crushing capacity had to reach 300 tonnes per hour to meet our crushing demand,” comments technician Christoph Koman from Swietelsky Tunnelbau. “The disassembly, lowering and re-assembly in the tunnel went well, and since April 2017, the unit has proven itself reliable and powerful enough to meet our capacity requirements,” Koman says.

Twin tunnel started from the middle

The Semmering Base Tunnel is part of the huge trans-European high-speed railway project, starting from Gdynia, Poland, and ending in Ravenna, Italy. Because of the mountain areas, several long tunnels are being dug, especially in Austria. The projects consist of twin tunnels with total lengths of 27.3 kilometers, bored by ARGE Tunnel Fröschschnitzgraben, a joint venture between Implenia and Swietelsky Tunnelbau. The new tunnel, together with Koralmbahn, will shorten the travel time between Vienna and Klagenfurt from four hours to less than two-and-a-half hours. The contract of the joint venture is the middle tunnel section, 24 km in length. Because of the varying rock conditions, it was decided to start the project from the middle of the tunnel by boring two 400-metre-deep shafts. After completing the shafts and caverns in March 2017, the tunneling work started in both directions in March 2017. The tunnel is seven meters wide and ten meters high. In addition, a 25-meter-wide and 17-meter-high rescue tunnel is being bored. All the blasted materials are lifted through the shaft.

Lokotrack lowered in three parts

The Metso Tampere Works designed the LT106E jaw plant so that the chassis can be split easily into two parts. In addition, the feeder was disassembled for lowering down with the elevator. Down at a depth of 400 m, the Lokotrack was assembled again to be ready for crushing.

Being fully electric, the LT106E is fed by wheel loaders, which carry the blasted materials from both tunnel heads. The feed is 0–600 mm in size, and the task of the C106 jaw-operated plant with an 85 mm closed side setting is to make sure that all the rocks being elevated are smaller than 150 mm.

Two big elevators lift the crushed materials up 400 meters to ground level, with each batch weighing 65–70 tonnes.

The extracted materials to be crushed contain a variety of gneiss and slate, and are very abrasive, too.

Promising start to a 1.2-million-tonne job

After two months of crushing operations, Christoph Koman is confident about the capability of Metso’s Lokotrack to handle the required amount of 1.2 million tonnes. The start has been promising, with no extra stoppages.

“We appreciate the reliability and crushing capacity of our Lokotrack. The unit runs smoothly, meeting our need of approximately 8–10 hours per day, and it meets the planned capacity of 300 tonnes per hour. The full unit capacity will be needed by next year at the latest, when we have to process the biggest material volumes.”

“Metso’s LT106E jaw plant has proven to be a reliable crushing plant causing no stoppages in our materials processing,” says technician Christoph Koman from Swietelsky Tunnelbau.

“This jaw plant with IC steering is easy to use for our operators. The adjustable hydraulic crusher setting is also a big plus – we do not need to stop crushing while adjusting the jaw. This adds to our operational uptime,” Koman adds.

From bunker up and 2.9 km with conveyors

After primary crushing, the rock is temporarily stored underground with hoppers. Two elevators with a combined capacity of 800 tonnes per hour take the material to the surface. At the surface, the aggregates are transported with static conveyors 2.9 km away for filling. Due to the varying geology, the extracted aggregates cannot be used, for example, to produce concrete or road base.