Unique protection against excavation by blasting in the style of Formula 1
LKAB is extracting ore in the open-pit mine in Svappavaara. At the time of the blasting, the area must be thoroughly cleared.
“A large mining pit means that the blasting areas are also larger,” explains Sweco’s consultant Ingemar Stenman, who works as a foreman at the LKAB Svappavaara construction site.
“Rocks really fly then – and they are big,” he continues. And there have been incidents. The old buildings are often very perforated. “Therefore, the vital parts of the pellet plant, such as the control equipment, the boiler house and the ovens, must be protected.”
Critical functions must be protected during blasting
NYAB was given the task of building and protecting two transformer buildings, where all LKAB Svappavaara’s electricity runs. These units must operate without interruption and the continuous blasting in the open-pit mine is a risk factor. If a large stone hits the units, the entire LKAB Svappavaara may be cut off from electricity. NYAB also received an order to create special shelters to protect vital buildings from the rocks flown by the blasts.
Unique protection from rock shards
Sweco’s innovative designer suggested a different approach for LKAB: using a specially designed safety net, such as Formula 1 uses to protect drivers and spectators along the tracks. The net is manufactured in Switzerland and can withstand very high loads. Similar protective nets were developed for installation in an upright position, attached to a solid steel fence. NYAB installed them horizontally in Svappavaara, for the first time in Sweden.
Net that stops avalanches and downhill skiers
The Swiss company Geobrugg, which supplied the net and steel frames, is an expert in various kinds of protective nets. Originally developed to stop avalanches and rocks in the Swiss Alps, the nets are now used for tunnels and downhill skiing routes and in motor sports. This is the first time that they are being used to protect a target from shards of falling rocks.
The Geobrugg net has a decelerating function that is designed to absorb the force of up to 500 kg of falling stones. The solution consists of a double net. The lighter top net has a stronger net underneath to absorb the greatest forces.
“Formula 1’s cutting-edge technology has been modified for the construction project,” says Stenman, continuing:
“It has been great working with NYAB. I have worked with quite a few entrepreneurs and NYAB has been an excellent partner so far. They are reliable, the timetables have been met, and the documentation is top notch.”
Facts about LKAB Svappavaara
LKAB has invested SEK 5 million in two open-pit mines and a production plant in Svappavaara, located forty kilometers southeast of Kiruna. The mining product is iron ore, which is enriched and processed into iron ore pellets. It is a processed product that is supplied to steel mills around the world. Expansion of the mine requires a larger crushing capacity, which is the reason for constructing new crushing plants, transformers and pumping stations, among others, in the area. The mines have been fully operational since spring 2017. Svappavaara, which produces up to two million metric tons annually, is going to be LKAB’s second largest mine.
Contents of the project
- new transformer building constructed from concrete elements
- excavation work
- concrete work, slabs, foundations
- steel frames around and over buildings
- installation of a protective net in four buildings.