Enhancement mechanisms of tetrapotassium pyrophosphate on flotation separation of pyrite from fine serpentine

Abstract

During the serpentine-contained sulfide ores flotation process, the presence of serpentine slimes will intensively deteriorate the flotation performance of sulfide ores due to hetero-coagulation. To handle this issue, tetrapotassium pyrophosphate (TKPP) was used as a novel depressant in this work. Micro-flotation results revealed that the addition of 5 g/L fine serpentine particle (−10 µm) caused a substantial reduction of approximately 82.5 % in pyrite recovery at pH 9. However, the detrimental impact of fine serpentine could be efficiently mitigated by the application of 30 mg/L TKPP, with a marked increase in pyrite recovery from 10.15 % to 91.25 %. The underlying mechanisms were elucidated using various characterization methods, revealing a significant shift in the surface charge of serpentine from positive to negative upon the addition of 30 mg/L TKPP, while the surface charge of pyrite remained largely unchanged. Consequently, a well-dispersion state of the mixed minerals pulp was achieved due to the identical surface charge. The alteration mechanisms of TKPP on serpentine involved the selective adsorption through forming P-O-Mg bonds and the accelerated decomposition of Mg²⁺ from serpentine. This study highlights the promising role of TKPP in reducing Mg in sulfide concentrator, proving a feasible solution for sulfide beneficiation operations.