I wrote about the mine after my winter trip http://naturallore.wordpress.com/2009/02/11/winter-in-lapland-2009/ but never expected to be given the opportunity to visit it as it is not open to public viewing.
We arrived at the mine just before six in the evening and had to visit security to check-in. Because Ingvar only speaks Swedish, Finnish and Saami and I only speak a little Swedish and no Finnish or Saami, his brother-in-law Kjell would be my guide.
Here is the processed ore which has been brought to the surface and is waiting to be loaded on to trains to be taken to sea ports at Lulea and Narvik.
Here is a piece of un-processed ore which I was given
and here is the processed ore in pellet form
As we drove below ground I was not sure what to expect, but I did not expect two lanes of traffic (including large lorries) to be coming and going. (Now I should mention here that although I got some really nice video footage, my digital camera did not perform as well as I had hoped!!)
The two main haulage levels are at 815 and 1000 metres in the Malmberget mine (Malm as I understand being the Saami word for Iron ore). At each of these levels there are huge crushers through which the mined material is deposited.
12 huge mine trucks are operated at these levels. I was fortunate enough to be offered a lift in one of these trucks with Veronica and Ann-Sofia. The trucks are driven to vertical shafts where the driver (in this case Ann-Sofia) controls loading from inside the cab of the truck by remote control. The fully-loaded truck is then driven to a discharge station and the ore is emptied into a crusher bin. This is also controlled from the cab of the truck. The ore is fed into the crusher and crushed into lumps of about 100 mm in diameter.
The ore then travels along a 1700 metre conveyor belt and from there is lifted to the surface by two 23 tonne skips at 16m per second.
The huge machinery required for drilling, setting explosive charges, rock supporting, loading and so on (here’s me next to a Toro loader)
has to be serviced and maintained below ground and so there is a very impressive workshop
I travelled 7km below the surface during my trip and one of the things I found most surprising was just how hot it was lower down. I only had a t-shirt on under my high-vis. jacket but I was sweating a lot. There are a complex system of fans and pipes which provide fresh air and remove stale air.
The explosive used when development drilling is a water resistant emulsion, which is pumped into pre drilled holes through a plastic hose. A scaling truck mounted with a hammer drill is used to remove loose rock after the explosion. Reinforcing bolts are grouted in 27mm holes to support the rock and shotcrete (a 3-5cm thick support layer) is sprayed over the hole rock surface.
In production drilling the charging holes are filled with kimlux a bulk emulsion explosive. The charging operation is automatic once the hose is in the hole.
You can read more about the whole process here; http://www.lkab.com/?openform&id=443A
Many thanks to LKAB for allowing me to visit the mine and to Ingvar, Kjell, Veronica and Ann-Sofia for making my tour very enjoyable.