A review of the physicochemical properties and flotation of pyrrhotite superstructures (4C – Fe7S8/ 5C – Fe9S10) in Ni‐Cu sulphide mineral processing

Abstract

AbstractPyrrhotite is one of the most abundant sulphide gangue minerals in base metal mining operations. It has little economic value and is a significant contributor of SO2 emissions at the smelting stage, thus it is rejected in most concentrators, requiring a concerted effort to ensure it is well separated from valuable minerals. The mineral processing of pyrrhotite is generally understood, however it has many complex crystallographic structures (superstructures) that behave differently in the flotation pulp for which the information is sparse and dispersed throughout the literature. Traditionally, the superstructures were largely isolated into magnetic/non–magnetic circuits and floated separately. Many operations have now transitioned away from magnetic separators, and treat the superstructures in the same flotation circuit where their flotation responses are quite different. Historically, it was perceived that the superstructures behaved virtually the same; whereas, recent work has clearly demonstrated that there are quantifiable differences in their flotation responses. The available information is scattered in the literature and is also plagued with many contradictions, making it very difficult for researchers to retrieve relevant information pertaining to the superstructures. This review aims to reduce the confusion by summarizing the superstructure nomenclature, characterization methods, aqueous stability, surface charges and superstructure‐reagent interactions, and available flotation data.