Formation of Hematite Whiskers during Magnetite Concentrate Oxidation

Abstract

Iron ore pellets prepared from magnetite concentrate are strengthened by oxidation of magnetite to hematite during pellet firing. In the present work, hematite whiskers were observed to grow on the oxidized surface of magnetite concentrate particles, over the entire temperature range studied (800°C to 950°C). The whisker thickness increased from approximately 30 nm for oxidation at 800°C to 200 nm at 950°C. The whiskers likely act as bridges between concentrate particles during pellet firing, contributing to pellet strength.

Hematite whiskers formed on magnetite particles during oxidation in air for 10 minutes at (a) 800°C, (b) 850°C, (c) 900°C, and (d) 950°C.