Pellets are manufactured in the pelletising plant from iron ore concentrate. The pellets are heated in a large furnace prior to onward transport to the ports.
In the pelletising plant, pellets are produced from the iron ore concentrate from the concentration plant. The pellets are dried, sintered and cooled before they are ready to be transported to the ports. LKAB has six pelletising plants: three in Kiruna, two in Malmberget and one in Svappavaara. The total capacity of the plants amounts to approximately 28 million tonnes of processed iron ore products per year.
The pellets are formed
In the pelletising plant, a clay mineral, bentonite, is added as a binder in the iron ore concentrate. Pellets with a diameter of around 10 mm are then formed in large, rotating drums. When the pellets have been rolled, they are transported for drying and pre-heating.
Drying and pre-heating
Drying and pre-heating increase the strength of the pellets. In the process, large amounts of energy are generated when the magnetite oxidised to form haematite, which reduces the energy requirement by 60 percent. As LKAB has two different types of pelletising plant – straight grate and great kiln plants – the drying process varies slightly.
In Malmberget's two pelletising plants, the entire process takes place on an endless conveyor belt. In Svappavaara's and Kiruna's pelletising plants, the process takes place in three different machine units: drying and pre-heating, heating in a rotating kiln, and cooling in a rotating cooler.
In order for the pellets to achieve their final properties, they have to be sintered, which means that the pellets are heated so that the iron ore particles partially melt together. After the pellets have been sintered at approximately 1,250°C, they can cope with a load of up to 250 kg.
After sintering, the red-hot pellets are cooled down to approximately 50°C and then moved to storage areas under the pelletising plant pending shipment.
When the pellets are ready, it is time for onward transport by train to the ports in Narvik and Luleå, where they are loaded and then delivered by boat to steel customers around the world.
- Pelletisation is a process where iron ore concentrate is mixed with additives and binder and rolled together into balls.
- The finished iron ore products are known as pellets.
- LKAB produces two types of pellets: blast furnace pellets and direct reduction pellets.
- The size, high iron content and well balanced additives in the pellets provide steelworks with several production engineering and financial benefits.
- Due to the fact that the magnetite is converted into haematite during the heating process, heat is generated which is used to heat up the furnace in which the pellets are heated.