ABSTRACT
The LKAB iron ore mines in Kiruna, Sweden, are located above the Arctic Circle. Two underground mines, located at Kiruna and Malmsberget, employ sublevel caving method, to produce 30Mt/y of iron ore. Much of the mining operation is automated – for instance, the production drilling rigs, loading machines and transport systems on the new main haulage level are remote-controlled. The magnetite ore is crushed, ground, screened and upgraded by magnetic separation techniques. The iron ore concentrate is pelletised using bentonite as a binder. The LKAB complex demonstrates how continuous improvements in technologies
could bring about high productivity, while at the same time reducing water and air pollution (Nordstrom, 2001). Mining and process water goes through large pond systems, to facilitate the removal of the sludge by sedimentation. The water is then pumped to the clarifying ponds from which the process water is recirculated. Since 1980, LKAB’s atmospheric emissions have been halved, while the production of pellets has doubled. The external energy consumption in the pelletising plants which was 639 MJ (million joules)/t of pellets in 1970 has been brought down to 250 MJ/t in 2000. The following air pollutants are produced in the process of pelletisation:
(i) Fine dust, mainly composed of iron oxides, before induration, (ii) Sulphur dioxide, from sulphur in the fuel, and sulphides in green pellets, (iii) Hydrogen fluoride and hydrochloric acid from apatite residues in green pellets, (iv) Nitrogen oxides, from nitrogen in the fuel and in the atmosphere.
