Improvements on industrial iron ore flotation using a novel co-depressant

Laboratorial and industrial trials were conducted at Companhia Siderurgica Nacional (CSN), Casa de Pedra mine, using a novel co-depressant developed by Georgia-Pacific (GPR-855), in association with corn starch, as depressant. Bench flotation experiments were performed partially replacing starch by GPR-855. The best results were achieved with 30% replacement ratio, obtaining an increase of 3.8% on mass recovery (2.5 percentage points, "p.p.") and 1.8% on iron recovery (1.5 p.p.), compared to the reference condition. Silica on concentrate was slightly higher than the reference condition. An industrial trial was conducted at CSN's beneficiation plant to validate these results, adding GPR-855 (240 g/t) directly into the process at the same point of gelatinized starch solution dosage (560 g/t). GPR-855 replaced partially starch, in the same ratio (30%) of the best condition indicated by the lab trials. The industrial results surpassed the values achieved at the laboratory scale, with significant improvement on mass recovery (5.1 p.p. or 8.6 %) and iron recovery (7.3 p.p. or 9.0%). The iron content on tailings was reduced in 30%, with lower silica assay on concentrate, compared to the base condition.