Oxidative Flotation Separation of Chalcopyrite and Pyrite Using K₂FeO₄ in Seawater

ABSTRACT

The oxidative flotation separation of chalcopyrite from pyrite in weak alkaline seawater solution was investigated using potassium ferrate (K₂FeO₄) as the oxidizing reagent. The optimal K₂FeO₄ concentration of 0.25 kg/t was found to strongly depress pyrite (from 88.05% to 7.92%) but insignificantly influence chalcopyrite (remaining at around 93%). K₂FeO₄ oxidized pyrite to form hydrophilic Fe₂O₃, Fe(OH)₃, FeOOH, and Fe₂(SO₄)₃ that covering on pyrite surface to prevent the adsorption of collector sodium butyl xanthate (SBX), thereby depressing pyrite flotation. Although a small amount of hydrophilic species was formed on chalcopyrite surface after the addition of K₂FeO₄, some hydrophobic substances such as S₂^2-/S_n^2-/S⁰ were also observed, resulting in an unaffected overall floatability. Further, density functional theory (DFT) calculation proved that the activity of Fe on chalcopyrite surface was much lower than that on pyrite. Therefore, this study provides a green way to separate chalcopyrite from pyrite effectively in a low-alkali seawater system, which is of significance to the separation of sulfide minerals in the fresh water-lack areas.

KEYWORDS:

• Seawater flotation
• pyrite
• chalcopyrite
• potassium ferrate
• selective oxidation

Acknowledgements

The authors acknowledged the financial supports from the National Natural Science Foundation of China under the projects of 51974215.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/08827508.2022.2155958

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [51974215].