Mitigação dos efeitos de cátions Ca2+ na flotação catiônica reversa de minério de ferro

Abstract

The current iron ore scenario presents various challenges; the hematitedeposits are close to being depleted and, thereby, the exploitation of the itabirite deposits begins. Concomitant with this movement, the maximum use of the current processing plants units is a goal. The Serra da Serpentina Project,= developed by Vale, is an important vector for the reclamation of low grade itabirites from the Iron Quadrangle. The critical point in this project option is the transportation of the ore (through a pipeline) between the mine and the plant, separated by a distance of 150km. The most serious issues in a long distance pulp pumping system like this are the obstruction and compaction of the settledmaterial inside the pipe (plug formation). An alternative for preventing theoccurrence of these problems is the addition of lime to the transported pulp. However, this reagent can bring deleterious effects on subsequent processes, especially on flotation, due to the presence of Ca2+ cations. To do so In order to achieve this goal, an evaluation of the use of different types of collectors (EDAC, MDB 1520, 1521 e 1325, Flotigam 5806), complexants (Floticor SI 7020) and frothers (Montanol 800) on flotation with lime and pH studies with the best condition of reagent dosing were performed, aiming maximum floatability. The standard rougher/cleaner flotation test used as reference without lime produced a pellet feed with grades of 0.66% silica on the concentrate and 29.81% iron on the tailings. The addition of lime affects the product quality directly, once noneof the tests presented results with SiO2<1.00% on the concentrate. Among the reagents that were tested, the use of the EDTA complexant with the EDA-C amine and the corn grits stands out. It can lower the silica grade on the concentrate and reduces the iron partition on the tailings, resulting in grades of 0.61% and 23.96%, respectively. The results showed that it is possible to obtain a concentrate with the quality in the project assumptions, SiO2 lower than 1.00%, even after the addition of lime to pump the ground material.