Exploration of a novel depressant polyepoxysuccinic acid for the flotation separation of pentlandite from lizardite slimes

Lizardite is representative of a group of serpentine minerals that coexists with nickel sulfide minerals, and the lizardite slime coating that easily forms on surfaces during mineral processing, making it difficult for beneficiation. In this study, a biodegradable polyepoxysuccinic acid (PESA) was introduced as a novel depressant to eliminate the adverse effects of lizardite slimes on pentlandite flotation. The results of microflotation tests and adsorption measurements showed that PESA addition considerably increased the separation efficiency of pentlandite from lizardite slimes, which could be attributed to the improvement of collector adsorption density on the pentlandite surface. Zeta potential measurements and DLVO calculations showed that the lizardite surface charge changed from positive to negative in the presence of PESA, and the resulting electrostatic repulsion caused hetero-dispersion between pentlandite and lizardite particles. Consequently, a collector could adsorb onto the exposed pentlandite surface, restoring the floatability of pentlandite. X-ray photoelectron spectroscopy (XPS) analysis was used to characterize the chemical interactions between PESA and the Mg sites on the lizardite surface. These results demonstrate that PESA can be used as an effective depressant for removing lizardite slimes from the pentlandite surface in a flotation system.