Carla Lopes (asker) Sep 12, 2012:

for example: The resources and targets are mainly within the early Proterozoic Middleback Subgroup sequence of banded iron formations (BIF) that host the historically important and currently operating iron ore mines of the Middleback Range (Onesteel Ltd). The extensive iron formations of Eyre Peninsula contain significant inferred resources of hematite and/or magnetite banded iron formation. Both historical and recent assays and metallurgical work have confirmed their potential and furthermore, the compositions of magnetic separations are favourable with high iron and low silica, alumina, phosphorous, alkalis and manganese.
Three categories of iron ore have been considered:

massive hematite ore (as traditionally mined) with Fe > 56% and low impurities (eg. phosphorous and silica);
hematite-rich BIF or jaspilite (interbanded hematite, quartz and/or iron silicates) with Fe >30%; and
magnetite-rich BIF (interbanded magnetite, quartz, marble and/or iron silicates) with magnetite content as determined by magnetic Davis Tube Separation (DTS)
>20% by weight.

The first category has traditionally been regarded as ‘direct shipping ore’ that could be exported without the need for benefic

Mauro Lando Sep 12, 2012:

mais contexto Carla se você pudesse por pelo menos a frase completa, seria mas fácil de ajuda-la.