The iron deposits of the Northern Iron System are hosted in the Precambrian rocks of the Itacaiunas Supergroup. The basement of the region consists of the Pium Complex ortho-granulites, and Xingu Complex gneiss and migmatites. The volcanics and sediments of the Itacaiunas Supergroup overlie the basement, and are in turn overlain by Aguas Claras clastic sediments. Granites, gabbros, and granitoids intrude the sedimentary sequence. The Carajas ores are hosted by the Grao Para Group of the Itacaiunas Supergroup, composed of meta-basalts, meta-sediments, ironstones, and meta-rhyolites. The ore deposits lie within an approximately 300 to 400 meters thick banded chert-hematite jaspilite unit that occurs between thick volcanic units.

The lower volcanic unit is the Parauapebas Formation (4,000 to 6,000 meters thick), and consists of bimodal volcanics (dominantly massive, vesicular and porphyritic flows and agglomerate breccias of metabasalt, meta-basaltic andesite and meta-trachyandesites), with subordinate (10 to 15 percent) meta- rhyolitic tuffs and flows.

The Carajas Formation hosts the deformed banded-iron formations (BIFs) with some interbedded mafic meta-volcanics. The Cigarra Formation (upper volcanic unit) is similar to that of the Parauapebas Formation with mixed meta-sediments (fine grained tuffs, tuffaceous siitstones, phyllites, cherts and greywacke). The volcanic sequence has generally been weathered to a depth of 100 to 150 meters. The oxidation is ........

Iron ore Northern System operations are located at Carajás, State of Pará in Brazil.

Northern System includes mining complexes:
- Serra Norte (three main mining areas and three beneficiation plants);
- Serra Sul (one main mining area and one beneficiation plant);
- Serra Leste (one mining area and one beneficiation plant).

Serra Norte
The Serra Norte Complex corresponds to deposits called N1, N2, N3, N4 and N5. The mines in operation are N4E, N4W and N5. Projects N1 and N2 are expected to start up in 2026 and project N3 is expected to start up in 2023.

N4 and N5 mines, currently in operation, utilize open pit mining and are operated by large loading and hauling equipment, namely, hydraulic excavators with loading capacity up to 80 ton, cable excavators with loading capacity up to 109 ton and front-end-loader with loading capacity of 72.6 ton. The haulage is carried out by truck with payload capacity of 400, 363 and 290 Tons. In some regions of these mines, where maximum relevant iron ore caves are presented, continuous miners are utilized, which eliminates drilling and blasting thereby reducing ground vibrations caused by blasting and avoiding damage to the caves near the mining areas.

The mining method at Serra Norte is open pit, as a normal standard operation used across the mining industry. Part of the material is free digging and other parts require blasting. The ore is loaded into the haul road trucks and d ........

In Serra Norte, two of the beneficiation plants apply natural moisture beneficiation process, consisting of crushing and screening, and the one of the plants applies both natural moisture and wet beneficiation process in distinct lines. Wet beneficiation process consists simply of sizing operations, including screening, hydrocycloning, crushing and filtration. Output from this site consists of sinter feed, pellet feed and lump ore. Serra Leste and Serra Sul natural moisture beneficiation process consists of crushing and screening. Serra Sul and Serra Leste produce only sinter feed.

Serra Sul
Serra Sul processing plant annual capacity is 90 million tons of iron ore, with 3 lines of 30 million tons per year each.

The Truckless System delivers ore to a homogenization stockpile. After the pile, the material is directed to the primary screening where the oversize (+90 mm) is directed to the secondary crushing and the undersize together with the secondary crushing ........