A comparative study of flotation of stockpile fines from mining of a nickel-copper sulphide ore

Ore samples from Onaping area stockpiles of Falconbridge were studied using batch flotation tests to investigate the effect of stockpiling conditions on grade-recovery performance along with slurry characterization, effect of blending, pH, size by size flotation performance of pentlandite, pyrrhotite and chalcopyrite.; The samples from stockpiles produced inferior nickel grade-recovery compared to fresh ore, which was attributable to two factors. First, a significant dilution effect was observed due to the nearly complete flotation of pyrrhotite. Secondly, while pyrrhotite from stockpiled ore became highly floatable, the same stockpiling conditions caused nickel losses that were attributable to non-floatability of some pentlandite.; There was generally insignificant difference in flotation of fresh and blended samples when the blending cases involved 27.4 and 50.2% stockpile samples. At 81.5% blending case, degraded grade-recovery appeared to be significant. There was a small, but noticeable amount of nickel loss for this case.; Pentlandite recoveries decreased for blending cases both in the fines, coarse sizes, and to some extent in the intermediate sizes as compared to the case with a fresh sample. In contrast, pyrrhotite indicated higher recoveries in the fines as well as in the coarse sizes. For chalcopyrite, the recoveries for blends were higher than fresh ore in the coarse size range while being lower in the fine size range compared to the fresh ore.; A kinetic analysis of these samples has also been performed. Two approaches of first order flotation kinetics (by Kelsall and Agar, respectively) have been used to estimate the flotation rate constants of pentlandite and pyrrhotite in stockpile samples and fresh sample to show the effect of stockpiling.; The impact of laboratory oxidation up to 7 months was investigated with respect to grinding stage, which involved an analysis of the flotation behaviour with oxidation taking place before and after grinding. The latter case resulted in several times more nickel losses and poorer selectivity between pentlandite and pyrrhotite.; A novel application of a 23 factorial design revealed important information on main and interaction effects of TETA, EDTA and KAX on oxidized pentlandite and pyrrhotite as well as their stage-wise dependence on these reagents.