Comparison of Flotation of Cu-Ni Sulfide Ores Containing Different Non-magnetic/Magnetic Pyrrhotite Ratios

The floatability of non-magnetic (Non-Mag) & magnetic (Mag) pyrrhotite (Po) in Cu-Ni sulfide ores (chalcopyrite-pentlandite) is an important area of research that is receiving more attention as concentrators seek to remove more Po from their final Ni concentrate. Based on both lab-scale and industrial data available in the current literature, it appears both Po polymorphs exhibit different flotation responses mainly due to their surface chemical differences, which is the result of their different crystal structures. This preliminary study summarizes the bench-scale Denver cell flotation results (coarse and fines: +38 and -38um, respectively) of three Cu-Ni sulfide ore bodies containing 30%, 50%, and 95% Non-Mag Po (balance being Mag Po). The main goals were to assess whether Po type had an impact on total Po recovery and pyrrhotite-pentlandite (Po-Pn) selectivity both in the coarse and fines fractions, +38 and -38um, respectively. For the three ores (all size fractions combined), the results indicate that Non-mag Po is much more floatable than Mag Po, increasing Non-Mag Po feed content increased total Po recovery, consequently, Pn selectivity was poorer against Non-mag Po than Mag Po. Comparing coarse (+38um) and fines (-38um), Po-Pn selectivity curves showed much poorer selectivity in the fines over coarse sizes (attributed to poor floatability of fine Pn). In the fines, the preliminary results showed that Non-mag Po was more floatable and that both polymorphs followed the trend of decreasing selectivity with increasing Mag Po feed content, this warrants further investigation with cyclosized fractions. For the coarse fraction, Pn selectivity against Non-mag Po was poorer than Mag Po. The findings from this study demonstrate that there are indeed quantifiable differences in the flotation responses of the polymorphs, which are primarily the result of their unique crystal structures and therefore different surface chemistries.