The effect of heat treatment on the magnetic properties of pyrite

The effect of thermal treatment on the magnetic properties of pyrite was investigated. Untreated pyrite showed evidence of both paramagnetic and ferromagnetic components. After heat treatment, the saturation magnetisation increased considerably until 800 °C when the magnetisation decreased, and then increased again after 900 °C. These changes are due to phase changes induced by oxidation. The wet magnetic recovery of the untreated sample was 25%, which increased to over 90% after treatment at 500 °C. The recovery of the magnetic fraction plateaus after treatment at higher temperatures, implying that a sample magnetisation greater than 5 kA m−1 leads to a recovery greater than 90% for this size fraction.