The Kiruna iron ore mine located southwest of the eponymous town of Kiruna in Sweden. It is the most important mine in the LKAB ( Luossavaara - Kiirunavaara Aktiebolaget ) and is considered the world's largest iron ore mine The mine wins in Teilsohlenbruchbau from the Erzberg Kiirunavaara quality phosphorus-containing magnetite.
- 3.1 hoisting plant
- 5.1 -345 m
- 5.2 -540 - m level
- 5.3 -775 - m level
- 5.4 -1045 - m level
- 5.5 1365 - m level
Geography and Geology
The mining area Kiruna is located north of the Arctic Circle in the province of Norrbotten County. In addition to the two deposits Kiirunavaara and Luossavaara, including the deposits Rektorn, Per Geijer seam, seam Henry, Haukivaara, Nukutusvaara and Tuolluvaara to the station. The degradation of Luossavaara has been closed since 1985.
26 million tons of crude ore from the pit Annually funded, with the expansion of the new base or platform to -1365 meters is from 2013, the production can be increased to 33 million tons of crude ore. 19 million tonnes of finished products are produced from the raw ore, with the largest part will be shipped as a pellet. For transportation to the ports of Narvik and Luleå Swedish Erzbahn used.
The Kiruna - seam provides by its high magnetite content, the second strongest magnetic anomaly of the earth Represents the measured at the surface maximum of 70,000 nT is about as strong as the magnetic field normal. Even at 400 km altitude could be determined by the ESA satellite Swarm still 10 nT. The seam is about four kilometers long and an average of eighty meters thick. The thickness increases to 150 to 180 meters in depth and to the north. It falls by 50 to 60 degrees and strokes in a northeasterly direction. The total depth of the deposit is unknown, but it is certainly enough to two kilometers.
The deposit was about 1.6 billion years ago by the precipitation of iron-rich solutions on a syenite porphyry basis after intense volcanism. The seam was overshadowed by other volcanic deposits of rhyolite and sediments before it was dumped in the present situation. The deposit consists almost exclusively of magnetite and apatite. The stone contains up to 60 % iron, and an average of 0.9 % of phosphorus. The phosphorus content is derived from the locally trapped apatite. The number of inclusions increases against the bedrock and to the south.
Initially, the seam stockpiled approximately 1.8 billion tons of ore, of which approximately one billion tons have been mined. The operator LKAB estimated in 2011 that 590 million tons in 1365 m still secure inventories are above the newly developed main haulage level, a further 76 million tonnes are considered probable reserves. The iron content of these stocks is above 47%. Below the new sole 328 million tons of ore are still suspected. The iron content decreases with depth more, but also decreases the amount of phosphorus.
Refining Ores and ore
In the pit of Kiruna magnetite is encouraged. The iron ore is broken by the removal of a grain size of about ten centimeters. Magnetic separation of the ore from the gangue of iron content to about 62 % is concentrated. Thereafter, the material is ground in mills to a particle size of about 0.05 mm. The resulting thin liquid sludge is floated to remove the phosphorus fractions and has an iron content of about 68 %. The resultant after drying, fine ore is partly supplied in the form of iron works, but usually further processed into more transportable pellets having a diameter of about ten millimeters.
For the preparation of low-viscosity mud with additives such as dolomite, olivine, limestone and quartzite is mixed, which are necessary as a binder and for use as a burden in the blast furnace. The binder is bentonite. After drying the slurry to about 9 % moisture, the pellets produced in rotating drums. They are then dried, pre-heated and fired at 1250 ° C. Due to the firing process the magnetite ore is converted to hematite and loses its magnetism.
Although in the area of the mine to the surface pinging are visible, the city of Kiruna was hardly affected by mining long time. Only the south of the lake Luossajärvi located Quartier Ön was abandoned in the 1960s and 1970s, and as a fenced premises. With the planned expansion of mining in the north, it was decided in June 2010 to relocate the city five kilometers to the east. Already in June 2007, had the southern part of the lake Luossajärvi be drained. The degradation including began about six months later. On 31 August 2012, the now -west running from Kiirunavaara line of Swedish iron ore railway was put into operation. By 2013, the Federal Highway and the historic buildings Bolagshotellet and Hjalmar Lundbohmsgården will be affected by mining subsidence.
The Kiirunavaara was first mentioned in writing in 1696, but was not worth a ore mining in spite of the rich presence for a long time. The site was too remote in an inhospitable environment and the phosphorus-containing ore could not be processed with the then available technologies. The ore was interesting until the invention of the Thomas process in the 1870s, because that could also phosphorus-containing ores are processed. After the Swedish iron ore railway was completed, the reduction began in 1900 in the industrial style.
The extraction was carried out until 1957 exclusively in the open pit, then the underground mining was gradually introduced to the mining was stopped altogether about 1962 days. Underground was partially Firstenstoßbau room and pillar, later exclusively used Teilsohlenbruchbau.
The ore is recovered in eight different mining areas. The routes are superimposed at a distance of 28.5 meters and 25 meters side by side. The triggered each after midnight blasting dissolves about 8500 tons of debris that is brought about role groups with driving loaders and crashed into this roughly classified. On the main floor, the material is taken over by mine cars and brought to breakers. The crushed to approximately 10 cm grain size raw ore is overthrown by the lying under the crusher rollers in Skips and promoted the day.
The mine is accessed via five spiral lines and weathered with ten ventilation shafts.
The bulk material is brought to the day over a number supplied by ABB Skip conveyors. The promotion is done in two stages, with the bulk material is transferred to the 775 m level.
The lower level of the carrier is at -740 m and houses the equipment for four Skip conveyor which promote the debris from the 1045 - m level. A fifth plant is from 2012 promoting the raw ore from the new sole -1365 m. The upper level comprises seven Skip conveyors, whose machines are housed in the 1954 winding tower built on the Kiirunavaara. The cages can reach speeds of up to 17 meters per second.
The raw ore of the mine is processed by a screening plant, two concentrators and two pelletizing plants. Which went into operation on 17 June 2008 Rust rotary kiln pellet plant KK4 is the world's largest of its kind, can produce up to 6 million tonnes of pellets per year. The finished products of the mine are fine Inter and pellets.
A portion of the crude ore is transported with trains to Svappavaara and processed into pellets.
The soles of the Kiruna ore mine are named after the height in relation to today's tip of the Kiirunavaaras. The mountain peak is labeled 0 m, the headroom of the lift system is located at the level -142 m, the entrance to the pit at the level -230 m. The Kiirunavaara was originally higher, but the former mountain peak consisted of iron ore and was therefore removed in 1910. Over the years, the distance between the main soles is growing. The main levels of the mine are located at -275 m, -320 m, -420 m, -540 m, -775 m, -1045 m and -1365 m.
The first main sole was applied to the sole of the old open pit in the rock formations so that a mine train could bring the pre-crushed aggregate to the newly created Skip conveyor. Next, the first lying underground canteen and workshop was built on this base or platform. The sole housed until 1999, the visitor mine. On this sole intercourse also from 1953 to 1961, a standard gauge tramway to the staff, the Swedish Kiruna Under Jord ( KUJ, dt: Kiruna underground) was called.
540 - m level
In the 1960s, the second main sole was established and brought all production facilities of the 345 - m level here. Since the relocation of facilities to the deeper main sole some blank lines for breeding of shiitake mushrooms are used. On the sole of -540 m is also the current exhibition mine LKAB InfoMine.
775 - m level
1979, the next new main sole was established. First driverless mining trains and LHDs are used. The equipment operator sitting in a control room and run their vehicles with the help of joysticks and video monitors. One worker can operate up to three LHDs same time, because this automatically navigate the distance between the cross-passages and rolling holes and tilt the material itself active in this. The debris is taken manually controlled.
-1045 - m level
Since 1999, the main haulage level is -1045 m in operation that is to be used until 2018. On the lying 300 meters below sea level sole operate seven trains that are controlled from the control room on the 775 m level and promote each 500 tons of debris to the four crushers.
1365 - m level
October 28, 2008, LKAB decided to build another base or platform. This sole is to go into operation in 2012 and remain about 2030 in operation, the total investment is 1.7 billion U.S. dollars. Thus, the pit will be expanded and increased the annual production. The two main soles -1045 m and -1365 m be operated for about seven to eight years in parallel.
On the sole 1600 -ton trains are used on standard gauge tracks. They are drawn from the contact wire locomotives. The four-axle, 106 -ton locomotives are built by Schalke's ironworks.