Processing

In the ore processing plants at surface level, the crude ore is upgraded to pellets and fines. Ore is ground to a fine powder in several stages; then, undesirable components are removed by magnetic separators.

   The concentrate is mixed with water to form a slurry and pumped to the pelletizing plant. The slurry is then dewatered with large filters, and then mixed with binders and additives, depending on the type of pellet to be produced. Olivine, quartzite, limestone and dolomite are examples of additives.

   The mixture is fed into gigantic drums and rolled into small ‘green balls’. These are then, in the grate-kiln process in Kiruna and Svappavaara, heated in a large rotary kiln at 1,250°C to become pellets. This gives them the hard surface they need to withstand long transports by rail and ship.

   The red-hot pellets are cooled to about 50°C before they are tipped into an underground storage facility beneath the pelletizing plant. From there, they are automatically loaded to railway cars for further transport.

   Unlike pellets, fines must be sintered to larger pieces before the product can be used in blast furnaces. Fines from Malmberget is a screened product from the mine. It is processed in sorting and concentrating plants by dry and wet separation.

   The Kiruna processing plants produces different types of iron ore pellets to the Steel Industry. Only Malmberget has the capacity to produce fines, but the main product from Malmberget will also be pellets in the future.