Optimisation of the Flame Spheroidisation Process for the Rapid Manufacture of Fe 3 O 4 -Based Porous and Dense Microspheres.

The rapid, single-stage, flame-spheroidisation process, as applied to varying Fe 3 O 4 :CaCO 3 powder combinations, provides for the rapid production of a mixture of dense and porous ferromagnetic microspheres with homogeneous composition, high levels of interconnected porosity and microsphere size control. This study describes the production of dense (35-80 µm) and highly porous (125-180 µm) Ca 2 Fe 2 O 5 ferromagnetic microspheres. Correlated backscattered electron imaging and mineral liberation analysis investigations provide insight into the microsphere formation mechanisms, as a function of Fe 3 O 4 /porogen mass ratios and gas flow settings. Optimised conditions for the processing of highly homogeneous Ca 2 Fe 2 O 5 porous and dense microspheres are identified. Induction heating studies of the materials produced delivered a controlled temperature increase to 43.7 °C, indicating that these flame-spheroidised Ca 2 Fe 2 O 5 ferromagnetic microspheres could be highly promising candidates for magnetic induced hyperthermia and other biomedical applications.