Oxidation of magnetite concentrate powders during storage and drying

Oxidation during storage at room temperature was observed as well. The Fe2+content in a standard Luossavaara-Kiirunavaara (LKAB) pellet feed decreased by 0.3% Fe2+during 4 years of storage at room temperature. Oxidation during storage was completely hindered when the samples were stored in a freezer at −50 °C. Therefore, freezer storage is recommended for all magnetite reference materials. These materials are used over several years and are especially susceptible to oxidation because they are usually finely ground and high in Fe2+content. The results also show that if the magnetite sample has partly oxidized to γ-hematite, the oxidation curve obtained by TGA will overestimate the Fe2+content of the sample, if background correction is necessary.