It is a classical long-standing industrial problem to separate ferrous from non-ferrous metal sulphides, which is mainly done by froth flotation. This method is based on the differences in the surface chemistry of minerals. Therefore, most of the research in this area focuses on the understanding of the selective interactions of metal sulfides with surfactants. In contrast, we found that these minerals have catalytic activity and generate reactive oxygen species and hydrogen peroxide (H2O2), which can modify their interaction with surfactants. We studied the formation of hydrogen peroxide by sulfide minerals during grinding. It was found that pyrite (FeS2), chalcopyrite (CuFeS2), sphalerite (ZnS), and galena (PbS), which are the most abundant sulfide minerals on Earth, generate hydrogen peroxide during wet grinding in the presence and absence of dissolved oxygen in water and also when the freshly ground solids are placed in water immediately after dry grinding. I will present these results highlighting the necessity of revisiting the electrochemical and/or galvanic interactions between the grinding medium and sulphide minerals, and interaction mechanisms between pyrite and other sulphide minerals in terms of their flotation behaviour, leaching and environmental degradation in the context of inevitable hydrogen peroxide presence in aqueous suspensions of metal sulphides.

Unconventional interfacial reactivity of metal sulfides: Relation to mineral separation

256th National Meeting (2018)

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