PRODUCTION

 

The mine.

Nowadays the production at the mine is solely based on tunnel work, since the old method on shrinkage stopeing was abandoned. As mentioned in our historic summary the main production takes currently place at level 86z ( z=meters above sea-level). Here the mine extends over a distance of 3 km, and the main part of the limestone at level 86z and above has been removed by shrinkage stopeing. But at both ends of the mine we will now recover limestone at several levels, all the way up to the surface. In the western part of the mine the exploitation takes place below the old "Sjøflot" mine, which is located at level 160z and extends over a distance of about 1 km. By accessing new levels at 12 meters intervals we will eventually exploit the 2 mines together. At the same time we will continue to work our way downward to level 10z. Here the limestone remains untouched over the mine's entire extent and mining will mainly take place here. The reserves extend from "Årnes" in the west, where the limestone vein disappears into the sea, and east to "Rindalen" valley at a distance of 30 km. This implies based on a conservative estimate, that some 150 million metric tons of limestone are located here, but the quantity may as well be in the order of 500 million mt.

Production equipment.

We own 2 diesel hydraulic Atlas Copco tunnel-rigs. This entails significant savings in rigging costs and -time since the mine extends over such a large area and the drilling sites are located far apart. First a 4 x 7 meter pilot tunnel is drilled. Thereafter the remaining limestone width is stoped. The average tunnel size becomes some 7 meter in height and 15 meter in width.

For blasting purposes we own a specially constructed rig with a lift and air-compressors to blow the powder explosive (anfo) into the drilled holes. Ignition takes place by means of nonel-bade millisecond percussion caps.

After the blast, loose rock is removed by means of a hydraulic hammer and after this has been done no loose stones remain so that it is not necessary to bolt the remaining surface.

Loading is carried out by means of 20 mt GHH mine loaders and the stones are conveyed to the silo by means of Volvo-dump trucks. With transport distances approaching 3 km one way, it is necessary to maintain an adequate road standard. For this purpose we operate a 5 mt Gehl-scraper, witch uses rubble from the mine as road building material.

Crushing plant.

The first stage of the crushing process is carried out in a crusher witch is located inside the mountain between the levels 10z and 86z. First there is a mine silo with a storage capacity of 1000 mt, which is sufficient to cover the daily capacity of the cruching unit. The first unit is a 250 mt German Humbolt jaw-crusher. The size of the jaw is 1,20 x 1,40 m. The limestone is further crushed in a 50 mt cone crusher. A vibrating Svedala screen, screens the limestone before it is stored in silos witch are located inside the mountain. Three fractions have been obtained by then: 0-8, 8-25 and 25-80 mm. Transport to the quay is by means of a conveyer belt.

The second part of the crushing process takes place at the quay. A 36" Morgaardhammer crushes the limestone into smaller fractions. Storage of finished product takes place in five silos with a capacity of 500 mt each. On top of the silos there is a screening plant witch splits the material into the fractions 0-1, 1-3, 3-8, and 8-16 mm. We also have a storage building where we store 0-1 mm agricultural limestone, and open-air storage areas for 0-3 mm coarse agricultural limestone, 3-8 mm gravel and 0-8 mm rubble.

At the quay we also bag limestone in small - and big (portabulk) bags.

Finished product is dispatched by truck or loaded on vessels.

P1010005.jpg (59954 byte)
Loading

P1010003.jpg (73578 byte)
Loading

P1010012.jpg (100195 byte)
Dumper by the mine entrance

P1010016.jpg (48470 byte)
Tunnel drilling

P1010019.jpg (61155 byte)
Road grader

P1010020.jpg (85415 byte)
Tunnel drilling

P1010022.jpg (55999 byte)
View from tunnel-rig

P1010026.jpg (53261 byte)
Blasting

P1010029.jpg (70522 byte)
Blasting

P1010032.jpg (86784 byte)
Explosives connected before blasting

P1010035.jpg (63542 byte)
Quay structures

P1010036.jpg (58837 byte)
Quay