Characterisation and dissolution studies on natural and synthetic brannerites

The structural and leaching characteristics of titanate minerals such as brannerite is of interest from a hydrometallurgical processing perspective and due to the potential of this mineral to be used as a host material for the immobilization of radio isotopes found in nuclear waste. In this study two different brannerites were synthesised and characterised using X-ray diffraction, scanning electron microscopy - energy dispersive X-ray and diffuse reflectance infrared spectroscopy. A natural brannerite sample was also characterised using the aforementioned techniques. Characterisation studies revealed that in un-doped synthetic brannerite (UTi2O6) uranium was present only in the +4 oxidation state whereas in synthetic doped brannerite and natural brannerite uranium was found to be present in +4 and +5 oxidation states. Of the various brannerites studied un-doped synthetic brannerite underwent the highest extent of dissolution over the range of conditions studied, natural brannerite which had been pre-heated to convert it to a crystalline form was the most difficult to dissolve